adding hint to logger error message

src/pytorch_lightning/trainer/connectors/logger_connector/fx_validator.py

@@ -174,7 +174,7 @@ def check_logging(cls, fx_name: str) -> None:
             )
 
         if cls.functions[fx_name] is None:
-            raise MisconfigurationException(f"You can't `self.log()` inside `{fx_name}`.")
+            raise MisconfigurationException(f"You can't `self.log()` inside `{fx_name}`. HINT: You can still log directly to the logger by using `self.logger.experiment`.")
 
     @classmethod
     def get_default_logging_levels(