added final check in check_answer

app.py

@@ -58,6 +58,7 @@ def load_file(path: str) -> dict:
     
 def check_format(answer: str | list, *args, **kwargs) -> list:
     """Check if the answer is a list and not a nested list."""
+    # other args are ignored on purpose, they are there just for compatibility
     print("Checking format of the answer:", answer)
     if isinstance(answer, list):
         for item in answer:
@@ -69,7 +70,9 @@ def check_format(answer: str | list, *args, **kwargs) -> list:
     elif isinstance(answer, str):
         return [answer]
     elif isinstance(answer, dict):
-        raise TypeError(f"Final answer must be a list, not a dict. Please check the answer format.")
+        raise TypeError("Final answer must be a list, not a dict. Please check the answer format.")
+    else:
+        raise TypeError("Answer format not recognized. The answer must be either a list or a string.")
 
 
 ## tools definition