Fix do_after throwing on attaching to new entity (#1679)

Co-authored-by: Metal Gear Sloth <metalgearsloth@gmail.com>

Content.Client/GameObjects/Components/DoAfterComponent.cs

@@ -3,8 +3,10 @@ using System;
 using System.Collections.Generic;
 using Content.Client.GameObjects.EntitySystems.DoAfter;
 using Content.Shared.GameObjects.Components;
+using Robust.Client.GameObjects;
 using Robust.Shared.GameObjects;
 using Robust.Shared.GameObjects.Systems;
+using Robust.Shared.Interfaces.GameObjects;
 using Robust.Shared.Interfaces.Network;
 using Robust.Shared.Interfaces.Timing;
 using Robust.Shared.IoC;
@@ -38,6 +40,18 @@ namespace Content.Client.GameObjects.Components
             }
         }
 
+        public override void HandleMessage(ComponentMessage message, IComponent? component)
+        {
+            base.HandleMessage(message, component);
+            switch (message)
+            {
+                case PlayerDetachedMsg _:
+                    _doAfters.Clear();
+                    CancelledDoAfters.Clear();
+                    break;
+            }
+        }
+
         /// <summary>
         ///     Remove a DoAfter without showing a cancellation graphic.
         /// </summary>