Enable nullability in Content.Shared (#3626)

* Enable nullability in Content.Shared

* Fix null errors in server

* aye github i swear on me mom

Content.Client/Construction/ConstructionMenuPresenter.cs

@@ -6,7 +6,6 @@ using Content.Client.GameObjects.EntitySystems;
 using Content.Client.UserInterface;
 using Content.Client.Utility;
 using Content.Shared.Construction;
-using Content.Shared.GameObjects.Components;
 using Content.Shared.GameObjects.Components.Interactable;
 using Robust.Client.Graphics;
 using Robust.Client.Placement;
@@ -18,7 +17,6 @@ using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Localization;
 using Robust.Shared.Prototypes;
-using Robust.Shared.Utility;
 
 namespace Content.Client.Construction
 {
@@ -224,15 +222,21 @@ namespace Content.Client.Construction
             var startNode = graph.Nodes[prototype.StartNode];
             var targetNode = graph.Nodes[prototype.TargetNode];
 
-            var path = graph.Path(startNode.Name, targetNode.Name);
+            if (!graph.TryPath(startNode.Name, targetNode.Name, out var path))
+            {
+                return;
+            }
 
             var current = startNode;
-
             var stepNumber = 1;
 
             foreach (var node in path)
             {
-                var edge = current.GetEdge(node.Name);
+                if (!current.TryGetEdge(node.Name, out var edge))
+                {
+                    continue;
+                }
+
                 var firstNode = current == startNode;
 
                 if (firstNode)

Content.Client/GameObjects/Components/Atmos/GasAnalyzerMenu.cs

@@ -165,7 +165,7 @@ namespace Content.Client.GameObjects.Components.Atmos
                     TemperatureHelpers.KelvinToCelsius(state.Temperature))
             });
             // Return here cause all that stuff down there is gas stuff (so we don't get the seperators)
-            if (state.Gases.Length == 0)
+            if (state.Gases == null || state.Gases.Length == 0)
             {
                 return;
             }

Content.Client/GameObjects/Components/Construction/ConstructionGhostComponent.cs

@@ -27,8 +27,13 @@ namespace Content.Client.GameObjects.Components.Construction
 
             if (!_prototypeManager.TryIndex(Prototype.Graph, out ConstructionGraphPrototype? graph)) return;
             var startNode = graph.Nodes[Prototype.StartNode];
-            var path = graph.Path(Prototype.StartNode, Prototype.TargetNode);
+
-            var edge = startNode.GetEdge(path[0].Name);
+            if (!graph.TryPath(Prototype.StartNode, Prototype.TargetNode, out var path) ||
+                !startNode.TryGetEdge(path[0].Name, out var edge))
+            {
+                return;
+            }
+
             edge.Steps[0].DoExamine(message, inDetailsRange);
         }
     }

Content.Client/GameObjects/EntitySystems/DragDropSystem.cs

@@ -20,6 +20,7 @@ using Robust.Shared.Localization;
 using Robust.Shared.Log;
 using Robust.Shared.Maths;
 using Robust.Shared.Prototypes;
+using Robust.Shared.Utility;
 using DrawDepth = Content.Shared.GameObjects.DrawDepth;
 
 namespace Content.Client.GameObjects.EntitySystems
@@ -217,8 +218,11 @@ namespace Content.Client.GameObjects.EntitySystems
             {
                 return false;
             }
+
+            DebugTools.AssertNotNull(_dragger);
+
             // still in range of the thing we are dragging?
-            if (!_interactionSystem.InRangeUnobstructed(_dragger, _dragDropHelper.Dragged))
+            if (!_interactionSystem.InRangeUnobstructed(_dragger!, _dragDropHelper.Dragged))
             {
                 return false;
             }

Content.Server/AI/Operators/Inventory/CloseStorageOperator.cs

@@ -66,7 +66,7 @@ namespace Content.Server.AI.Operators.Inventory
 
             if (storageComponent.Open)
             {
-                var activateArgs = new ActivateEventArgs {User = _owner, Target = _target};
+                var activateArgs = new ActivateEventArgs(_owner, _target);
                 storageComponent.Activate(activateArgs);
             }
 

Content.Server/AI/Operators/Inventory/OpenStorageOperator.cs

@@ -43,7 +43,7 @@ namespace Content.Server.AI.Operators.Inventory
 
             if (!storageComponent.Open)
             {
-                var activateArgs = new ActivateEventArgs {User = _owner, Target = _target};
+                var activateArgs = new ActivateEventArgs(_owner, _target);
                 storageComponent.Activate(activateArgs);
             }
 

Content.Server/GameObjects/Components/Atmos/GasAnalyzerComponent.cs

@@ -239,7 +239,7 @@ namespace Content.Server.GameObjects.Components.Atmos
                     var activeHandEntity = handsComponent.GetActiveHand?.Owner;
                     if (activeHandEntity == null || !activeHandEntity.TryGetComponent(out GasAnalyzerComponent? gasAnalyzer))
                     {
-                        serverMsg.Session.AttachedEntity.PopupMessage(Loc.GetString("You need a Gas Analyzer in your hand!"));
+                        serverMsg.Session.AttachedEntity?.PopupMessage(Loc.GetString("You need a Gas Analyzer in your hand!"));
                         return;
                     }
 

Content.Server/GameObjects/Components/Body/MechanismComponent.cs

@@ -88,7 +88,7 @@ namespace Content.Server.GameObjects.Components.Body
             }
             else // If surgery cannot be performed, show message saying so.
             {
-                eventArgs.Target.PopupMessage(eventArgs.User,
+                eventArgs.Target?.PopupMessage(eventArgs.User,
                     Loc.GetString("You see no way to install the {0}.", Owner.Name));
             }
         }

Content.Server/GameObjects/Components/Body/Part/BodyPartComponent.cs

@@ -155,7 +155,7 @@ namespace Content.Server.GameObjects.Components.Body.Part
             }
             else // If surgery cannot be performed, show message saying so.
             {
-                eventArgs.Target.PopupMessage(eventArgs.User,
+                eventArgs.Target?.PopupMessage(eventArgs.User,
                     Loc.GetString("You see no way to install {0:theName}.", Owner));
             }
         }

Content.Server/GameObjects/Components/Body/Surgery/SurgeryToolComponent.cs

@@ -16,8 +16,6 @@ using Robust.Server.Player;
 using Robust.Shared.GameObjects;
 using Robust.Shared.Localization;
 using Robust.Shared.Log;
-using Robust.Shared.Prototypes;
-using Robust.Shared.Serialization;
 using Robust.Shared.Serialization.Manager.Attributes;
 using Robust.Shared.ViewVariables;
 
@@ -246,7 +244,9 @@ namespace Content.Server.GameObjects.Components.Body.Surgery
         private void HandleReceiveMechanism(int key)
         {
             // TODO: sanity checks to see whether user is in range, user is still able-bodied, target is still the same, etc etc
-            if (!_optionsCache.TryGetValue(key, out var targetObject) ||
+            if (BodyCache == null ||
+                !_optionsCache.TryGetValue(key, out var targetObject) ||
+                targetObject is not MechanismComponent target ||
                 PerformerCache == null ||
                 !PerformerCache.TryGetComponent(out IActorComponent? actor))
             {
@@ -254,20 +254,22 @@ namespace Content.Server.GameObjects.Components.Body.Surgery
                 return;
             }
 
-            var target = targetObject as MechanismComponent;
-
             CloseSurgeryUI(actor.playerSession);
             _callbackCache?.Invoke(target, BodyCache, this, PerformerCache);
         }
 
         private void NotUsefulPopup()
         {
+            if (PerformerCache == null) return;
+
             BodyCache?.Owner.PopupMessage(PerformerCache,
                 Loc.GetString("You see no useful way to use {0:theName}.", Owner));
         }
 
         private void NotUsefulAnymorePopup()
         {
+            if (PerformerCache == null) return;
+
             BodyCache?.Owner.PopupMessage(PerformerCache,
                 Loc.GetString("You see no useful way to use {0:theName} anymore.", Owner));
         }

Content.Server/GameObjects/Components/Buckle/BuckleComponent.cs

@@ -13,7 +13,6 @@ using Content.Shared.GameObjects.Components.Strap;
 using Content.Shared.GameObjects.EntitySystems.ActionBlocker;
 using Content.Shared.GameObjects.Verbs;
 using Content.Shared.Interfaces;
-using Content.Shared.Interfaces.GameObjects.Components;
 using Content.Shared.Utility;
 using Robust.Server.GameObjects;
 using Robust.Shared.Containers;
@@ -237,7 +236,7 @@ namespace Content.Server.GameObjects.Components.Buckle
 
         public override bool TryBuckle(IEntity? user, IEntity to)
         {
-            if (!CanBuckle(user, to, out var strap))
+            if (user == null || !CanBuckle(user, to, out var strap))
             {
                 return false;
             }

Content.Server/GameObjects/Components/Instruments/InstrumentComponent.cs

@@ -15,8 +15,6 @@ using Robust.Shared.GameObjects;
 using Robust.Shared.Localization;
 using Robust.Shared.Network;
 using Robust.Shared.Players;
-using Robust.Shared.Prototypes;
-using Robust.Shared.Serialization;
 using Robust.Shared.Serialization.Manager.Attributes;
 using Robust.Shared.ViewVariables;
 
@@ -201,11 +199,11 @@ namespace Content.Server.GameObjects.Components.Instruments
                         {
                             if (_laggedBatches == (int) (maxMidiLaggedBatches * (1 / 3d) + 1))
                             {
-                                Owner.PopupMessage(InstrumentPlayer.AttachedEntity,
+                                InstrumentPlayer.AttachedEntity?.PopupMessage(
                                     Loc.GetString("Your fingers are beginning to a cramp a little!"));
                             } else if (_laggedBatches == (int) (maxMidiLaggedBatches * (2 / 3d) + 1))
                             {
-                                Owner.PopupMessage(InstrumentPlayer.AttachedEntity,
+                                InstrumentPlayer.AttachedEntity?.PopupMessage(
                                     Loc.GetString("Your fingers are seriously cramping up!"));
                             }
                         }
@@ -360,11 +358,11 @@ namespace Content.Server.GameObjects.Components.Instruments
                         stun.Stun(1);
                         Clean();
                     }
+
+                    Owner.PopupMessage(mob, "Your fingers cramp up from playing!");
                 }
 
                 InstrumentPlayer = null;
-
-                Owner.PopupMessage(mob, "Your fingers cramp up from playing!");
             }
 
             _timer += delta;

Content.Server/GameObjects/Components/Interactable/WelderComponent.cs

@@ -21,8 +21,6 @@ using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Localization;
 using Robust.Shared.Players;
-using Robust.Shared.Prototypes;
-using Robust.Shared.Serialization;
 using Robust.Shared.Serialization.Manager.Attributes;
 using Robust.Shared.Utility;
 using Robust.Shared.ViewVariables;
@@ -139,20 +137,24 @@ namespace Content.Server.GameObjects.Components.Interactable
         {
             if (!WelderLit)
             {
-                if(!silent) Owner.PopupMessage(user, Loc.GetString("The welder is turned off!"));
+                if (!silent && user != null)
+                    Owner.PopupMessage(user, Loc.GetString("The welder is turned off!"));
+
                 return false;
             }
 
             if (!CanWeld(value))
             {
-                if(!silent) Owner.PopupMessage(user, Loc.GetString("The welder does not have enough fuel for that!"));
+                if (!silent && user != null)
+                    Owner.PopupMessage(user, Loc.GetString("The welder does not have enough fuel for that!"));
+
                 return false;
             }
 
             if (_solutionComponent == null)
                 return false;
 
-            bool succeeded = _solutionComponent.TryRemoveReagent("chem.WeldingFuel", ReagentUnit.New(value));
+            var succeeded = _solutionComponent.TryRemoveReagent("chem.WeldingFuel", ReagentUnit.New(value));
 
             if (succeeded && !silent)
             {
@@ -192,7 +194,7 @@ namespace Content.Server.GameObjects.Components.Interactable
                 return true;
             }
 
-            if (!CanLitWelder())
+            if (!CanLitWelder() && user != null)
             {
                 Owner.PopupMessage(user, Loc.GetString("The welder has no fuel left!"));
                 return false;

Content.Server/GameObjects/Components/Items/Storage/ServerStorageComponent.cs

@@ -23,8 +23,6 @@ using Robust.Shared.Log;
 using Robust.Shared.Map;
 using Robust.Shared.Network;
 using Robust.Shared.Players;
-using Robust.Shared.Prototypes;
-using Robust.Shared.Serialization;
 using Robust.Shared.Serialization.Manager.Attributes;
 using Robust.Shared.ViewVariables;
 
@@ -481,7 +479,7 @@ namespace Content.Server.GameObjects.Components.Items.Storage
 
         void IActivate.Activate(ActivateEventArgs eventArgs)
         {
-            ((IUse) this).UseEntity(new UseEntityEventArgs { User = eventArgs.User });
+            ((IUse) this).UseEntity(new UseEntityEventArgs(eventArgs.User));
         }
 
         /// <summary>

Content.Server/GameObjects/Components/Morgue/MorgueTrayComponent.cs

@@ -15,13 +15,9 @@ namespace Content.Server.GameObjects.Components.Morgue
 
         void IActivate.Activate(ActivateEventArgs eventArgs)
         {
-            if(Morgue != null && !Morgue.Deleted && Morgue.TryGetComponent<MorgueEntityStorageComponent>(out var comp))
+            if (Morgue != null && !Morgue.Deleted && Morgue.TryGetComponent<MorgueEntityStorageComponent>(out var comp))
             {
-                comp.Activate(new ActivateEventArgs()
+                comp.Activate(new ActivateEventArgs(eventArgs.User, Morgue));
-                {
-                    User = eventArgs.User,
-                    Target = Morgue
-                });
             }
         }
     }

Content.Server/GameObjects/EntitySystems/Click/InteractionSystem.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Collections.Generic;
 using System.Linq;
 using System.Threading.Tasks;
 using Content.Server.GameObjects.Components.Items.Storage;
@@ -26,7 +25,6 @@ using Robust.Shared.IoC;
 using Robust.Shared.Log;
 using Robust.Shared.Map;
 using Robust.Shared.Maths;
-using Robust.Shared.Physics;
 using Robust.Shared.Players;
 
 namespace Content.Server.GameObjects.EntitySystems.Click
@@ -143,7 +141,7 @@ namespace Content.Server.GameObjects.EntitySystems.Click
             }
 
             // all activates should only fire when in range / unbostructed
-            var activateEventArgs = new ActivateEventArgs { User = user, Target = used };
+            var activateEventArgs = new ActivateEventArgs(user, used);
             if (activateEventArgs.InRangeUnobstructed(ignoreInsideBlocker: true, popup: true))
             {
                 activateComp.Activate(activateEventArgs);
@@ -432,10 +430,7 @@ namespace Content.Server.GameObjects.EntitySystems.Click
                 return;
 
             var attackBys = attacked.GetAllComponents<IInteractUsing>().OrderByDescending(x => x.Priority);
-            var attackByEventArgs = new InteractUsingEventArgs
+            var attackByEventArgs = new InteractUsingEventArgs(user, clickLocation, weapon, attacked);
-            {
-                User = user, ClickLocation = clickLocation, Using = weapon, Target = attacked
-            };
 
             // all AttackBys should only happen when in range / unobstructed, so no range check is needed
             if (attackByEventArgs.InRangeUnobstructed(ignoreInsideBlocker: true, popup: true))
@@ -474,7 +469,7 @@ namespace Content.Server.GameObjects.EntitySystems.Click
             if (message.Handled)
                 return;
 
-            var attackHandEventArgs = new InteractHandEventArgs { User = user, Target = attacked };
+            var attackHandEventArgs = new InteractHandEventArgs(user, attacked);
 
             // all attackHands should only fire when in range / unobstructed
             if (attackHandEventArgs.InRangeUnobstructed(ignoreInsideBlocker: true, popup: true))
@@ -534,7 +529,7 @@ namespace Content.Server.GameObjects.EntitySystems.Click
             // Try to use item on any components which have the interface
             foreach (var use in uses)
             {
-                if (use.UseEntity(new UseEntityEventArgs { User = user }))
+                if (use.UseEntity(new UseEntityEventArgs(user)))
                 {
                     // If a Use returns a status completion we finish our attack
                     return;
@@ -753,10 +748,7 @@ namespace Content.Server.GameObjects.EntitySystems.Click
                 return;
 
             var rangedAttackBys = attacked.GetAllComponents<IRangedInteract>().ToList();
-            var rangedAttackByEventArgs = new RangedInteractEventArgs
+            var rangedAttackByEventArgs = new RangedInteractEventArgs(user, weapon, clickLocation);
-            {
-                User = user, Using = weapon, ClickLocation = clickLocation
-            };
 
             // See if we have a ranged attack interaction
             foreach (var t in rangedAttackBys)

Content.Server/GameObjects/EntitySystems/ConstructionSystem.cs

@@ -352,11 +352,18 @@ namespace Content.Server.GameObjects.EntitySystems
                 return;
             }
 
+            var user = args.SenderSession.AttachedEntity;
+
+            if (user == null)
+            {
+                Logger.Error($"Client sent {nameof(TryStartStructureConstructionMessage)} with no attached entity!");
+                return;
+            }
+
             var startNode = constructionGraph.Nodes[constructionPrototype.StartNode];
             var targetNode = constructionGraph.Nodes[constructionPrototype.TargetNode];
             var pathFind = constructionGraph.Path(startNode.Name, targetNode.Name);
 
-            var user = args.SenderSession.AttachedEntity;
 
             if (_beingBuilt.TryGetValue(args.SenderSession, out var set))
             {

Content.Server/GameObjects/EntitySystems/PointingSystem.cs

@@ -69,7 +69,7 @@ namespace Content.Server.GameObjects.EntitySystems
                         ? viewerPointedAtMessage
                         : viewerMessage;
 
-                source.PopupMessage(viewer.AttachedEntity, message);
+                source.PopupMessage(viewerEntity, message);
             }
         }
 

Content.Shared/Construction/ConstructionGraphNode.cs

@@ -1,6 +1,6 @@
 using System;
 using System.Collections.Generic;
-using Robust.Shared.Prototypes;
+using System.Diagnostics.CodeAnalysis;
 using Robust.Shared.Serialization.Manager.Attributes;
 using Robust.Shared.ViewVariables;
 
@@ -12,12 +12,13 @@ namespace Content.Shared.Construction
     {
         [DataField("actions", serverOnly: true)]
         private List<IGraphAction> _actions = new();
+
         [DataField("edges")]
         private List<ConstructionGraphEdge> _edges = new();
 
         [ViewVariables]
-        [DataField("node")]
+        [DataField("node", required: true)]
-        public string Name { get; private set; }
+        public string Name { get; private set; } = default!;
 
         [ViewVariables]
         public IReadOnlyList<ConstructionGraphEdge> Edges => _edges;
@@ -27,9 +28,9 @@ namespace Content.Shared.Construction
 
         [ViewVariables]
         [DataField("entity")]
-        public string Entity { get; private set; }
+        public string? Entity { get; private set; }
 
-        public ConstructionGraphEdge GetEdge(string target)
+        public ConstructionGraphEdge? GetEdge(string target)
         {
             foreach (var edge in _edges)
             {
@@ -39,5 +40,10 @@ namespace Content.Shared.Construction
 
             return null;
         }
+
+        public bool TryGetEdge(string target, [NotNullWhen(true)] out ConstructionGraphEdge? edge)
+        {
+            return (edge = GetEdge(target)) != null;
+        }
     }
 }

Content.Shared/Construction/ConstructionGraphPrototype.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.IO;
 using Robust.Shared.Prototypes;
 using Robust.Shared.Serialization;
@@ -12,8 +13,8 @@ namespace Content.Shared.Construction
     public class ConstructionGraphPrototype : IPrototype, ISerializationHooks
     {
         private readonly Dictionary<string, ConstructionGraphNode> _nodes = new();
-        private readonly Dictionary<ValueTuple<string, string>, ConstructionGraphNode[]> _paths = new();
+        private readonly Dictionary<ValueTuple<string, string>, ConstructionGraphNode[]?> _paths = new();
-        private readonly Dictionary<string, Dictionary<ConstructionGraphNode, ConstructionGraphNode>> _pathfinding = new();
+        private readonly Dictionary<string, Dictionary<ConstructionGraphNode, ConstructionGraphNode?>> _pathfinding = new();
 
         [ViewVariables]
         [field: DataField("id", required: true)]
@@ -21,7 +22,7 @@ namespace Content.Shared.Construction
 
         [ViewVariables]
         [field: DataField("start")]
-        public string Start { get; }
+        public string? Start { get; }
 
         [DataField("graph", priority: 0)]
         private List<ConstructionGraphNode> _graph = new();
@@ -35,20 +36,30 @@ namespace Content.Shared.Construction
 
             foreach (var graphNode in _graph)
             {
+                if (string.IsNullOrEmpty(graphNode.Name))
+                {
+                    throw new InvalidDataException($"Name of graph node is null in construction graph {ID}!");
+                }
+
                 _nodes[graphNode.Name] = graphNode;
             }
 
-            if(string.IsNullOrEmpty(Start) || !_nodes.ContainsKey(Start))
+            if (string.IsNullOrEmpty(Start) || !_nodes.ContainsKey(Start))
                 throw new InvalidDataException($"Starting node for construction graph {ID} is null, empty or invalid!");
         }
 
-        public ConstructionGraphEdge Edge(string startNode, string nextNode)
+        public ConstructionGraphEdge? Edge(string startNode, string nextNode)
         {
             var start = _nodes[startNode];
             return start.GetEdge(nextNode);
         }
 
-        public ConstructionGraphNode[] Path(string startNode, string finishNode)
+        public bool TryPath(string startNode, string finishNode, [NotNullWhen(true)] out ConstructionGraphNode[]? path)
+        {
+            return (path = Path(startNode, finishNode)) != null;
+        }
+
+        public ConstructionGraphNode[]? Path(string startNode, string finishNode)
         {
             var tuple = new ValueTuple<string, string>(startNode, finishNode);
 
@@ -57,7 +68,7 @@ namespace Content.Shared.Construction
 
             // Get graph given the current start.
 
-            Dictionary<ConstructionGraphNode, ConstructionGraphNode> pathfindingForStart;
+            Dictionary<ConstructionGraphNode, ConstructionGraphNode?> pathfindingForStart;
             if (_pathfinding.ContainsKey(startNode))
             {
                 pathfindingForStart = _pathfinding[startNode];
@@ -76,8 +87,6 @@ namespace Content.Shared.Construction
             var path = new List<ConstructionGraphNode>();
             while (current != start)
             {
-                path.Add(current);
-
                 // No path.
                 if (current == null || !pathfindingForStart.ContainsKey(current))
                 {
@@ -86,6 +95,8 @@ namespace Content.Shared.Construction
                     return null;
                 }
 
+                path.Add(current);
+
                 current = pathfindingForStart[current];
             }
 
@@ -97,13 +108,13 @@ namespace Content.Shared.Construction
         ///     Uses breadth first search for pathfinding.
         /// </summary>
         /// <param name="start"></param>
-        private Dictionary<ConstructionGraphNode, ConstructionGraphNode> PathsForStart(string start)
+        private Dictionary<ConstructionGraphNode, ConstructionGraphNode?> PathsForStart(string start)
         {
             // TODO: Make this use A* or something, although it's not that important.
             var startNode = _nodes[start];
 
             var frontier = new Queue<ConstructionGraphNode>();
-            var cameFrom = new Dictionary<ConstructionGraphNode, ConstructionGraphNode>();
+            var cameFrom = new Dictionary<ConstructionGraphNode, ConstructionGraphNode?>();
 
             frontier.Enqueue(startNode);
             cameFrom[startNode] = null;

Content.Shared/Content.Shared.csproj

@@ -10,6 +10,7 @@
     <Configurations>Release;Debug</Configurations>
     <Platforms>AnyCPU</Platforms>
     <WarningsAsErrors>nullable</WarningsAsErrors>
+    <Nullable>enable</Nullable>
   </PropertyGroup>
   <Import Project="..\RobustToolbox\MSBuild\Robust.DefineConstants.targets" />
   <ItemGroup>

Content.Shared/GameObjects/Components/Inventory/SharedInventoryComponent.cs

@@ -1,11 +1,9 @@
 using System;
 using System.Collections.Generic;
 using Content.Shared.GameObjects.Components.Movement;
-using Content.Shared.GameObjects.EntitySystems.EffectBlocker;
 using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Reflection;
-using Robust.Shared.Prototypes;
 using Robust.Shared.Serialization;
 using Robust.Shared.Serialization.Manager.Attributes;
 using Robust.Shared.Utility;
@@ -16,16 +14,14 @@ namespace Content.Shared.GameObjects.Components.Inventory
 {
     public abstract class SharedInventoryComponent : Component, IMoveSpeedModifier
     {
-        // ReSharper disable UnassignedReadonlyField
+        [Dependency] protected readonly IReflectionManager ReflectionManager = default!;
-        [Dependency] protected readonly IReflectionManager ReflectionManager;
+        [Dependency] protected readonly IDynamicTypeFactory DynamicTypeFactory = default!;
-        [Dependency] protected readonly IDynamicTypeFactory DynamicTypeFactory;
-        // ReSharper restore UnassignedReadonlyField
 
         public sealed override string Name => "Inventory";
         public sealed override uint? NetID => ContentNetIDs.STORAGE;
 
         [ViewVariables]
-        protected Inventory InventoryInstance { get; private set; }
+        protected Inventory InventoryInstance { get; private set; } = default!;
 
         [ViewVariables]
         [DataField("Template")]
@@ -42,7 +38,7 @@ namespace Content.Shared.GameObjects.Components.Inventory
         {
             var type = ReflectionManager.LooseGetType(_templateName);
             DebugTools.Assert(type != null);
-            InventoryInstance = DynamicTypeFactory.CreateInstance<Inventory>(type);
+            InventoryInstance = DynamicTypeFactory.CreateInstance<Inventory>(type!);
         }
 
         /// <returns>true if the item is equipped to an equip slot (NOT inside an equipped container

Content.Shared/GameObjects/Components/Materials/MaterialComponent.cs

@@ -40,13 +40,13 @@ namespace Content.Shared.GameObjects.Components.Materials
         [DataDefinition]
         public class MaterialDataEntry : ISerializationHooks
         {
-            public object Key;
+            public object Key = default!;
 
-            [DataField("key")]
+            [DataField("key", required: true)]
-            public string StringKey;
+            public string StringKey = default!;
 
-            [DataField("mat")]
+            [DataField("mat", required: true)]
-            public string Value;
+            public string Value = default!;
 
             void ISerializationHooks.AfterDeserialization()
             {

Content.Shared/GameObjects/Components/SharedGasAnalyzerComponent.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Collections.Generic;
 using Robust.Shared.GameObjects;
 using Robust.Shared.Localization;
 using Robust.Shared.Serialization;
@@ -22,10 +21,10 @@ namespace Content.Shared.GameObjects.Components
         {
             public float Pressure;
             public float Temperature;
-            public GasEntry[] Gases;
+            public GasEntry[]? Gases;
-            public string Error = string.Empty;
+            public string? Error;
 
-            public GasAnalyzerBoundUserInterfaceState(float pressure, float temperature, GasEntry[] gases, string error = null)
+            public GasAnalyzerBoundUserInterfaceState(float pressure, float temperature, GasEntry[]? gases, string? error = null)
             {
                 Pressure = pressure;
                 Temperature = temperature;

Content.Shared/GameObjects/Components/SharedStackComponent.cs

@@ -76,7 +76,7 @@ namespace Content.Shared.GameObjects.Components
             return new StackComponentState(Count, MaxCount);
         }
 
-        public override void HandleComponentState(ComponentState curState, ComponentState nextState)
+        public override void HandleComponentState(ComponentState? curState, ComponentState? nextState)
         {
             if (curState is not StackComponentState cast)
             {

Content.Shared/GameObjects/EntitySystems/SharedInteractionSystem.cs

@@ -4,10 +4,8 @@ using Content.Shared.Interfaces.GameObjects.Components;
 using Content.Shared.Physics;
 using JetBrains.Annotations;
 using Robust.Shared.GameObjects;
-using Robust.Shared.IoC;
 using Robust.Shared.Localization;
 using Robust.Shared.Map;
-using Robust.Shared.Maths;
 using Robust.Shared.Physics;
 using Robust.Shared.Physics.Broadphase;
 
@@ -40,7 +38,7 @@ namespace Content.Shared.GameObjects.EntitySystems
             MapCoordinates origin,
             MapCoordinates other,
             int collisionMask = (int) CollisionGroup.Impassable,
-            Ignored predicate = null)
+            Ignored? predicate = null)
         {
             var dir = other.Position - origin.Position;
 
@@ -69,7 +67,7 @@ namespace Content.Shared.GameObjects.EntitySystems
             MapCoordinates origin,
             MapCoordinates other,
             int collisionMask = (int) CollisionGroup.Impassable,
-            IEntity ignoredEnt = null)
+            IEntity? ignoredEnt = null)
         {
             var predicate = ignoredEnt == null
                 ? null
@@ -111,7 +109,7 @@ namespace Content.Shared.GameObjects.EntitySystems
             MapCoordinates other,
             float range = InteractionRange,
             CollisionGroup collisionMask = CollisionGroup.Impassable,
-            Ignored predicate = null,
+            Ignored? predicate = null,
             bool ignoreInsideBlocker = false)
         {
             if (!origin.InRange(other, range)) return false;
@@ -132,7 +130,7 @@ namespace Content.Shared.GameObjects.EntitySystems
 
             foreach (var result in rayResults)
             {
-                if (!result.HitEntity.TryGetComponent(out IPhysBody p))
+                if (!result.HitEntity.TryGetComponent(out IPhysBody? p))
                 {
                     continue;
                 }
@@ -186,7 +184,7 @@ namespace Content.Shared.GameObjects.EntitySystems
             IEntity other,
             float range = InteractionRange,
             CollisionGroup collisionMask = CollisionGroup.Impassable,
-            Ignored predicate = null,
+            Ignored? predicate = null,
             bool ignoreInsideBlocker = false,
             bool popup = false)
         {
@@ -242,7 +240,7 @@ namespace Content.Shared.GameObjects.EntitySystems
             IComponent other,
             float range = InteractionRange,
             CollisionGroup collisionMask = CollisionGroup.Impassable,
-            Ignored predicate = null,
+            Ignored? predicate = null,
             bool ignoreInsideBlocker = false,
             bool popup = false)
         {
@@ -298,7 +296,7 @@ namespace Content.Shared.GameObjects.EntitySystems
             EntityCoordinates other,
             float range = InteractionRange,
             CollisionGroup collisionMask = CollisionGroup.Impassable,
-            Ignored predicate = null,
+            Ignored? predicate = null,
             bool ignoreInsideBlocker = false,
             bool popup = false)
         {
@@ -354,7 +352,7 @@ namespace Content.Shared.GameObjects.EntitySystems
             MapCoordinates other,
             float range = InteractionRange,
             CollisionGroup collisionMask = CollisionGroup.Impassable,
-            Ignored predicate = null,
+            Ignored? predicate = null,
             bool ignoreInsideBlocker = false,
             bool popup = false)
         {
@@ -408,7 +406,7 @@ namespace Content.Shared.GameObjects.EntitySystems
             ITargetedInteractEventArgs args,
             float range = InteractionRange,
             CollisionGroup collisionMask = CollisionGroup.Impassable,
-            Ignored predicate = null,
+            Ignored? predicate = null,
             bool ignoreInsideBlocker = false,
             bool popup = false)
         {
@@ -453,7 +451,7 @@ namespace Content.Shared.GameObjects.EntitySystems
             DragDropEventArgs args,
             float range = InteractionRange,
             CollisionGroup collisionMask = CollisionGroup.Impassable,
-            Ignored predicate = null,
+            Ignored? predicate = null,
             bool ignoreInsideBlocker = false,
             bool popup = false)
         {
@@ -521,7 +519,7 @@ namespace Content.Shared.GameObjects.EntitySystems
             AfterInteractEventArgs args,
             float range = InteractionRange,
             CollisionGroup collisionMask = CollisionGroup.Impassable,
-            Ignored predicate = null,
+            Ignored? predicate = null,
             bool ignoreInsideBlocker = false,
             bool popup = false)
         {

Content.Shared/Interfaces/GameObjects/Components/Interaction/IActivate.cs

@@ -23,8 +23,14 @@ namespace Content.Shared.Interfaces.GameObjects.Components
 
     public class ActivateEventArgs : EventArgs, ITargetedInteractEventArgs
     {
-        public IEntity User { get; set; }
+        public ActivateEventArgs(IEntity user, IEntity target)
-        public IEntity Target { get; set; }
+        {
+            User = user;
+            Target = target;
+        }
+
+        public IEntity User { get; }
+        public IEntity Target { get; }
     }
 
     /// <summary>

Content.Shared/Interfaces/GameObjects/Components/Interaction/IInteractHand.cs

@@ -20,8 +20,14 @@ namespace Content.Shared.Interfaces.GameObjects.Components
 
     public class InteractHandEventArgs : EventArgs, ITargetedInteractEventArgs
     {
-        public IEntity User { get; set; }
+        public InteractHandEventArgs(IEntity user, IEntity target)
-        public IEntity Target { get; set; }
+        {
+            User = user;
+            Target = target;
+        }
+
+        public IEntity User { get; }
+        public IEntity Target { get; }
     }
 
 

Content.Shared/Interfaces/GameObjects/Components/Interaction/IInteractUsing.cs

@@ -29,10 +29,18 @@ namespace Content.Shared.Interfaces.GameObjects.Components
 
     public class InteractUsingEventArgs : EventArgs, ITargetedInteractEventArgs
     {
-        public IEntity User { get; set; }
+        public InteractUsingEventArgs(IEntity user, EntityCoordinates clickLocation, IEntity @using, IEntity target)
-        public EntityCoordinates ClickLocation { get; set; }
+        {
-        public IEntity Using { get; set; }
+            User = user;
-        public IEntity Target { get; set; }
+            ClickLocation = clickLocation;
+            Using = @using;
+            Target = target;
+        }
+
+        public IEntity User { get; }
+        public EntityCoordinates ClickLocation { get; }
+        public IEntity Using { get; }
+        public IEntity Target { get; }
     }
 
     /// <summary>

Content.Shared/Interfaces/GameObjects/Components/Interaction/IRangedInteract.cs

@@ -23,9 +23,16 @@ namespace Content.Shared.Interfaces.GameObjects.Components
     [PublicAPI]
     public class RangedInteractEventArgs : EventArgs
     {
-        public IEntity User { get; set; }
+        public RangedInteractEventArgs(IEntity user, IEntity @using, EntityCoordinates clickLocation)
-        public IEntity Using { get; set; }
+        {
-        public EntityCoordinates ClickLocation { get; set; }
+            User = user;
+            Using = @using;
+            ClickLocation = clickLocation;
+        }
+
+        public IEntity User { get; }
+        public IEntity Using { get; }
+        public EntityCoordinates ClickLocation { get; }
     }
 
     /// <summary>

Content.Shared/Interfaces/GameObjects/Components/Interaction/IUse.cs

@@ -21,7 +21,12 @@ namespace Content.Shared.Interfaces.GameObjects.Components
 
     public class UseEntityEventArgs : EventArgs
     {
-        public IEntity User { get; set; }
+        public UseEntityEventArgs(IEntity user)
+        {
+            User = user;
+        }
+
+        public IEntity User { get; }
     }
 
     /// <summary>