Explicitly check hook signature (#7502)

panel/viewable.py

@@ -12,6 +12,7 @@
 
 import asyncio
 import functools
+import inspect
 import logging
 import os
 import sys
@@ -600,9 +601,9 @@ def _preprocess(self, root: 'Model', changed=None, old_models=None) -> None:
         changed = self if changed is None else changed
         hooks = self._preprocessing_hooks+self._hooks
         for hook in hooks:
-            try:
+            if len(inspect.signature(hook).parameters) >= 4:
                 hook(self, root, changed, old_models)
-            except TypeError:
+            else:
                 hook(self, root)
 
     def _render_model(self, doc: Optional[Document] = None, comm: Optional[Comm] = None) -> 'Model':