Fix being able to start pulling something while incapacitated. (#4240)

Content.Shared/Pulling/Components/SharedPullableComponent.cs

@@ -204,6 +204,11 @@ namespace Content.Shared.Pulling.Components
                 return false;
             }
 
+            if (!EntitySystem.Get<SharedPullingSystem>().CanPull(puller, Owner))
+            {
+                return false;
+            }
+
             if (_physics == null)
             {
                 return false;

Content.Shared/Pulling/Events/StartPullAttemptEvent.cs

@@ -0,0 +1,19 @@
+using Robust.Shared.GameObjects;
+
+namespace Content.Shared.Pulling.Events
+{
+    /// <summary>
+    ///     Directed event raised on the puller to see if it can start pulling something.
+    /// </summary>
+    public class StartPullAttemptEvent : CancellableEntityEventArgs
+    {
+        public StartPullAttemptEvent(IEntity puller, IEntity pulled)
+        {
+            Puller = puller;
+            Pulled = pulled;
+        }
+
+        public IEntity Puller { get; }
+        public IEntity Pulled { get; }
+    }
+}

Content.Shared/Pulling/SharedPullingSystem.cs

@@ -6,6 +6,7 @@ using Content.Shared.GameTicking;
 using Content.Shared.Input;
 using Content.Shared.Physics.Pull;
 using Content.Shared.Pulling.Components;
+using Content.Shared.Pulling.Events;
 using Content.Shared.Rotatable;
 using JetBrains.Annotations;
 using Robust.Shared.Containers;
@@ -237,5 +238,12 @@ namespace Content.Shared.Pulling
                     pulled.Transform.WorldRotation = newAngle;
             }
         }
+
+        public bool CanPull(IEntity puller, IEntity pulled)
+        {
+            var startPull = new StartPullAttemptEvent(puller, pulled);
+            RaiseLocalEvent(puller.Uid, startPull);
+            return !startPull.Cancelled;
+        }
     }
 }