Rehydratable component attaches spawned entities to grid or map.

Also fix crash when injecting rehydratable with a solution.
- Fixes #2969

Content.Server/GameObjects/Components/Chemistry/RehydratableComponent.cs

@@ -3,6 +3,7 @@ using Content.Server.Utility;
 using Content.Shared.Chemistry;
 using Content.Shared.GameObjects.EntitySystems;
 using Content.Shared.Interfaces.GameObjects.Components;
+using Content.Shared.Utility;
 using Robust.Shared.GameObjects;
 using Robust.Shared.Localization;
 using Robust.Shared.Serialization;
@@ -67,7 +68,8 @@ namespace Content.Server.GameObjects.Components.Chemistry
             Owner.PopupMessageEveryone(Loc.GetString("{0:TheName} expands!", Owner));
             if (!string.IsNullOrEmpty(_targetPrototype))
             {
-                Owner.EntityManager.SpawnEntity(_targetPrototype, Owner.Transform.Coordinates);
+                var ent = Owner.EntityManager.SpawnEntity(_targetPrototype, Owner.Transform.Coordinates);
+                ent.Transform.AttachToGridOrMap();
             }
             Owner.Delete();
         }

Content.Shared/GameObjects/Components/Chemistry/SharedSolutionContainerComponent.cs

@@ -171,8 +171,7 @@ namespace Content.Shared.GameObjects.Components.Chemistry
 
         private void SolutionChanged()
         {
-            EntitySystem.Get<ChemistrySystem>()
-                .HandleSolutionChange(Owner);
+            EntitySystem.Get<ChemistrySystem>().HandleSolutionChange(Owner);
         }
 
         private void ProcessReactions()
@@ -212,7 +211,7 @@ namespace Content.Shared.GameObjects.Components.Chemistry
 
         private void UpdateAppearance()
         {
-            if (!Owner.TryGetComponent<SharedAppearanceComponent>(out var appearance))
+            if (Owner.Deleted || !Owner.TryGetComponent<SharedAppearanceComponent>(out var appearance))
                 return;
 
             appearance.SetData(SolutionContainerVisuals.VisualState, GetVisualState());

Content.Shared/GameObjects/EntitySystems/ChemistrySystem.cs

@@ -36,6 +36,9 @@ namespace Content.Shared.GameObjects.EntitySystems
             foreach (var solutionChangeArg in solutionChangeArgs)
             {
                 solutionChangeArg.SolutionChanged(eventArgs);
+
+                if (owner.Deleted)
+                    return;
             }
         }
     }