Dont trigger event functions if the passed pointer is nil

PkmnLibSharp/Battling/Events/BattleEventListener.cs

@@ -51,6 +51,10 @@ namespace PkmnLibSharp.Battling.Events
 
         private async Task InternalRunner(IntPtr ptr)
         {
+            if (ptr == IntPtr.Zero)
+            {
+                return;
+            }
             var wrapped = WrapEventPtr(ptr);
             await _del.Invoke(wrapped);
         }