Removed the Sender object from events. If you needed this field, add it to the event class.

Content.Client/GameObjects/Components/IconSmoothing/IconSmoothComponent.cs

@@ -81,7 +81,7 @@ namespace Content.Client.GameObjects.Components.IconSmoothing
             base.Startup();
 
             SnapGrid.OnPositionChanged += SnapGridOnPositionChanged;
-            Owner.EntityManager.EventBus.RaiseEvent(Owner, new IconSmoothDirtyEvent(null, SnapGrid.Offset, Mode));
+            Owner.EntityManager.EventBus.RaiseEvent(new IconSmoothDirtyEvent(Owner,null, SnapGrid.Offset, Mode));
             if (Mode == IconSmoothingMode.Corners)
             {
                 var state0 = $"{StateBase}0";
@@ -203,12 +203,12 @@ namespace Content.Client.GameObjects.Components.IconSmoothing
             base.Shutdown();
 
             SnapGrid.OnPositionChanged -= SnapGridOnPositionChanged;
-            Owner.EntityManager.EventBus.RaiseEvent(Owner, new IconSmoothDirtyEvent(_lastPosition, SnapGrid.Offset, Mode));
+            Owner.EntityManager.EventBus.RaiseEvent(new IconSmoothDirtyEvent(Owner, _lastPosition, SnapGrid.Offset, Mode));
         }
 
         private void SnapGridOnPositionChanged()
         {
-            Owner.EntityManager.EventBus.RaiseEvent(Owner, new IconSmoothDirtyEvent(_lastPosition, SnapGrid.Offset, Mode));
+            Owner.EntityManager.EventBus.RaiseEvent(new IconSmoothDirtyEvent(Owner, _lastPosition, SnapGrid.Offset, Mode));
             _lastPosition = (Owner.Transform.GridID, SnapGrid.Position);
         }
 

Content.Client/GameObjects/Components/SubFloorHideComponent.cs

@@ -1,6 +1,7 @@
 using Robust.Client.Interfaces.GameObjects.Components;
 using Robust.Shared.GameObjects;
 using Robust.Shared.GameObjects.Components.Transform;
+using Robust.Shared.Interfaces.GameObjects;
 
 namespace Content.Client.GameObjects.Components
 {
@@ -32,7 +33,7 @@ namespace Content.Client.GameObjects.Components
             base.Startup();
 
             _snapGridComponent.OnPositionChanged += SnapGridOnPositionChanged;
-            Owner.EntityManager.EventBus.RaiseEvent(Owner, new SubFloorHideDirtyEvent());
+            Owner.EntityManager.EventBus.RaiseEvent(new SubFloorHideDirtyEvent(Owner));
         }
 
         /// <inheritdoc />
@@ -44,14 +45,22 @@ namespace Content.Client.GameObjects.Components
                 return;
 
             _snapGridComponent.OnPositionChanged -= SnapGridOnPositionChanged;
-            Owner.EntityManager.EventBus.RaiseEvent(Owner, new SubFloorHideDirtyEvent());
+            Owner.EntityManager.EventBus.RaiseEvent(new SubFloorHideDirtyEvent(Owner));
         }
 
         private void SnapGridOnPositionChanged()
         {
-            Owner.EntityManager.EventBus.RaiseEvent(Owner, new SubFloorHideDirtyEvent());
+            Owner.EntityManager.EventBus.RaiseEvent(new SubFloorHideDirtyEvent(Owner));
         }
     }
 
-    internal sealed class SubFloorHideDirtyEvent : EntitySystemMessage { }
+    internal sealed class SubFloorHideDirtyEvent : EntitySystemMessage
+    {
+        public IEntity Sender { get; }
+
+        public SubFloorHideDirtyEvent(IEntity sender)
+        {
+            Sender = sender;
+        }
+    }
 }

Content.Client/GameObjects/Components/WindowComponent.cs

@@ -31,7 +31,7 @@ namespace Content.Client.GameObjects.Components
             base.Startup();
 
             _snapGrid.OnPositionChanged += SnapGridOnPositionChanged;
-            Owner.EntityManager.EventBus.RaiseEvent(Owner, new WindowSmoothDirtyEvent());
+            Owner.EntityManager.EventBus.RaiseEvent(new WindowSmoothDirtyEvent(Owner));
 
             var state0 = $"{_stateBase}0";
             _sprite.LayerMapSet(CornerLayers.SE, _sprite.AddLayerState(state0));
@@ -54,7 +54,7 @@ namespace Content.Client.GameObjects.Components
 
         private void SnapGridOnPositionChanged()
         {
-            Owner.EntityManager.EventBus.RaiseEvent(Owner, new WindowSmoothDirtyEvent());
+            Owner.EntityManager.EventBus.RaiseEvent(new WindowSmoothDirtyEvent(Owner));
         }
 
         public void UpdateSprite()

Content.Client/GameObjects/EntitySystems/IconSmoothSystem.cs

@@ -53,11 +53,12 @@ namespace Content.Client.GameObjects.EntitySystems
             }
         }
 
-        private void HandleDirtyEvent(object sender, IconSmoothDirtyEvent ev)
+        private void HandleDirtyEvent(IconSmoothDirtyEvent ev)
         {
             // Yes, we updates ALL smoothing entities surrounding us even if they would never smooth with us.
             // This is simpler to implement. If you want to optimize it be my guest.
-            if (sender is IEntity senderEnt && senderEnt.IsValid() &&
+            var senderEnt = ev.Sender;
+            if (senderEnt.IsValid() &&
                 senderEnt.TryGetComponent(out IconSmoothComponent iconSmooth)
                 && iconSmooth.Running)
             {
@@ -137,15 +138,17 @@ namespace Content.Client.GameObjects.EntitySystems
     /// </summary>
     public sealed class IconSmoothDirtyEvent : EntitySystemMessage
     {
-        public IconSmoothDirtyEvent((GridId grid, MapIndices pos)? lastPosition, SnapGridOffset offset, IconSmoothingMode mode)
+        public IconSmoothDirtyEvent(IEntity sender, (GridId grid, MapIndices pos)? lastPosition, SnapGridOffset offset, IconSmoothingMode mode)
         {
             LastPosition = lastPosition;
             Offset = offset;
             Mode = mode;
+            Sender = sender;
         }
 
         public (GridId grid, MapIndices pos)? LastPosition { get; }
         public SnapGridOffset Offset { get; }
         public IconSmoothingMode Mode { get; }
+        public IEntity Sender { get; }
     }
 }

Content.Client/GameObjects/EntitySystems/MeleeWeaponSystem.cs

@@ -37,7 +37,7 @@ namespace Content.Client.GameObjects.EntitySystems
             }
         }
 
-        private void PlayWeaponArc(object sender, PlayMeleeWeaponAnimationMessage msg)
+        private void PlayWeaponArc(PlayMeleeWeaponAnimationMessage msg)
         {
             if (!_prototypeManager.TryIndex(msg.ArcPrototype, out MeleeWeaponAnimationPrototype weaponArc))
             {

Content.Client/GameObjects/EntitySystems/SubFloorHideSystem.cs

@@ -3,7 +3,6 @@ using Content.Shared.Maps;
 using Robust.Client.Interfaces.GameObjects.Components;
 using Robust.Shared.GameObjects.Components.Transform;
 using Robust.Shared.GameObjects.Systems;
-using Robust.Shared.Interfaces.GameObjects;
 using Robust.Shared.Interfaces.Map;
 using Robust.Shared.IoC;
 using Robust.Shared.Map;
@@ -32,15 +31,10 @@ namespace Content.Client.GameObjects.EntitySystems
             SubscribeEvent<SubFloorHideDirtyEvent>(HandleDirtyEvent);
         }
 
-        private void HandleDirtyEvent(object sender, SubFloorHideDirtyEvent ev)
+        private void HandleDirtyEvent(SubFloorHideDirtyEvent ev)
         {
-            if (!(sender is IEntity senderEnt))
+            var grid = _mapManager.GetGrid(ev.Sender.Transform.GridID);
-            {
+            var indices = grid.WorldToTile(ev.Sender.Transform.WorldPosition);
-                return;
-            }
-
-            var grid = _mapManager.GetGrid(senderEnt.Transform.GridID);
-            var indices = grid.WorldToTile(senderEnt.Transform.WorldPosition);
             UpdateTile(grid, indices);
         }
 

Content.Client/GameObjects/EntitySystems/VerbSystem.cs

@@ -112,7 +112,7 @@ namespace Content.Client.GameObjects.EntitySystems
             OpenContextMenu(entity, new ScreenCoordinates(_inputManager.MouseScreenPosition));
         }
 
-        private void FillEntityPopup(object sender, VerbSystemMessages.VerbsResponseMessage msg)
+        private void FillEntityPopup(VerbSystemMessages.VerbsResponseMessage msg)
         {
             if (_currentEntity != msg.Entity || !_entityManager.TryGetEntity(_currentEntity, out var entity))
             {

Content.Client/GameObjects/EntitySystems/WindowSystem.cs

@@ -1,4 +1,4 @@
-using System.Collections.Generic;
+using System.Collections.Generic;
 using Content.Client.GameObjects.Components;
 using JetBrains.Annotations;
 using Robust.Shared.GameObjects;
@@ -19,11 +19,11 @@ namespace Content.Client.GameObjects.EntitySystems
             SubscribeEvent<WindowSmoothDirtyEvent>(HandleDirtyEvent);
         }
 
-        private void HandleDirtyEvent(object sender, WindowSmoothDirtyEvent ev)
+        private void HandleDirtyEvent(WindowSmoothDirtyEvent ev)
         {
-            if (sender is IEntity senderEnt && senderEnt.HasComponent<WindowComponent>())
+            if (ev.Sender.HasComponent<WindowComponent>())
             {
-                _dirtyEntities.Enqueue(senderEnt);
+                _dirtyEntities.Enqueue(ev.Sender);
             }
         }
 
@@ -50,5 +50,11 @@ namespace Content.Client.GameObjects.EntitySystems
     /// </summary>
     public sealed class WindowSmoothDirtyEvent : EntitySystemMessage
     {
+        public IEntity Sender { get; }
+
+        public WindowSmoothDirtyEvent(IEntity sender)
+        {
+            Sender = sender;
+        }
     }
 }

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

@@ -35,7 +35,7 @@ namespace Content.Server.GameObjects.EntitySystems
         {
             base.Initialize();
 
-            SubscribeEvent<ExamineSystemMessages.RequestExamineInfoMessage>((sender, ev) => ExamineInfoRequest(ev));
+            SubscribeEvent<ExamineSystemMessages.RequestExamineInfoMessage>(ExamineInfoRequest);
 
             IoCManager.InjectDependencies(this);
         }

Content.Server/GameObjects/EntitySystems/CombatModeSystem.cs

@@ -31,7 +31,7 @@ namespace Content.Server.GameObjects.EntitySystems
                 InputCmdHandler.FromDelegate(CombatModeToggled));
         }
 
-        private void SetCombatModeActiveHandler(object sender, SetCombatModeActiveMessage ev)
+        private void SetCombatModeActiveHandler(SetCombatModeActiveMessage ev)
         {
             if (!TryGetCombatComponent(ev, out var combatModeComponent))
                 return;
@@ -39,7 +39,7 @@ namespace Content.Server.GameObjects.EntitySystems
             combatModeComponent.IsInCombatMode = ev.Active;
         }
 
-        private void SetTargetZoneHandler(object sender, SetTargetZoneMessage ev)
+        private void SetTargetZoneHandler(SetTargetZoneMessage ev)
         {
             if (!TryGetCombatComponent(ev, out var combatModeComponent))
                 return;

Content.Server/GameObjects/EntitySystems/HandsSystem.cs

@@ -65,7 +65,7 @@ namespace Content.Server.GameObjects.EntitySystems
             base.Shutdown();
         }
 
-        private static void HandleContainerModified(object sender, ContainerModifiedMessage args)
+        private static void HandleContainerModified(ContainerModifiedMessage args)
         {
             if (args.Container.Owner.TryGetComponent(out IHandsComponent handsComponent))
             {

Content.Server/GameObjects/EntitySystems/MoverSystem.cs

@@ -80,7 +80,7 @@ namespace Content.Server.GameObjects.EntitySystems
             _audioSystem = EntitySystemManager.GetEntitySystem<AudioSystem>();
         }
 
-        private static void PlayerAttached(object sender, PlayerAttachSystemMessage ev)
+        private static void PlayerAttached(PlayerAttachSystemMessage ev)
         {
             if (!ev.Entity.HasComponent<IMoverComponent>())
             {
@@ -88,7 +88,7 @@ namespace Content.Server.GameObjects.EntitySystems
             }
         }
 
-        private static void PlayerDetached(object sender, PlayerDetachedSystemMessage ev)
+        private static void PlayerDetached(PlayerDetachedSystemMessage ev)
         {
             if(ev.Entity.HasComponent<PlayerInputMoverComponent>())
             {

Content.Server/GameObjects/EntitySystems/StorageSystem.cs

@@ -29,7 +29,7 @@ namespace Content.Server.GameObjects.EntitySystems
             }
         }
 
-        private static void HandleEntityRemovedFromContainer(object sender, EntRemovedFromContainerMessage message)
+        private static void HandleEntityRemovedFromContainer(EntRemovedFromContainerMessage message)
         {
             var oldParentEntity = message.Container.Owner;
 
@@ -39,7 +39,7 @@ namespace Content.Server.GameObjects.EntitySystems
             }
         }
 
-        private static void HandleEntityInsertedIntoContainer(object sender, EntInsertedIntoContainerMessage message)
+        private static void HandleEntityInsertedIntoContainer(EntInsertedIntoContainerMessage message)
         {
             var oldParentEntity = message.Container.Owner;
 

Content.Server/GameObjects/EntitySystems/VerbSystem.cs

@@ -20,8 +20,8 @@ namespace Content.Server.GameObjects.EntitySystems
         {
             base.Initialize();
 
-            SubscribeEvent<RequestVerbsMessage>((sender, ev) => RequestVerbs(ev));
+            SubscribeEvent<RequestVerbsMessage>(RequestVerbs);
-            SubscribeEvent<UseVerbMessage>((sender, ev) => UseVerb(ev));
+            SubscribeEvent<UseVerbMessage>(UseVerb);
 
             IoCManager.InjectDependencies(this);
         }

Content.Server/GameTicking/GameRules/RuleDeathMatch.cs

@@ -46,7 +46,7 @@ namespace Content.Server.GameTicking.GameRules
             _playerManager.PlayerStatusChanged -= PlayerManagerOnPlayerStatusChanged;
         }
 
-        private void _onMobDamageStateChanged(object sender, MobDamageStateChangedMessage message)
+        private void _onMobDamageStateChanged(MobDamageStateChangedMessage message)
         {
             _runDelayedCheck();
         }