Add a check to make sure the method has a __name__ member before trying to print it

direct/src/showbase/Messenger.py

@@ -634,7 +634,10 @@ class Messenger:
             functionName = method.im_class.__name__ + '.' + \
                 method.im_func.__name__
         else:
-            functionName = method.__name__
+            if hasattr(method, "__name__"):
+                functionName = method.__name__
+            else:
+                return ""
         return functionName
 
     def __eventRepr(self, event):