more fixes

Author: rishabhpoddar

supertokens_python/recipe/session/recipe_implementation.py

@@ -182,9 +182,9 @@ async def get_session(
         user_context: Optional[Dict[str, Any]] = None,
     ) -> Optional[SessionContainer]:
         if (
-            anti_csrf_check is not False
-            and self.config.anti_csrf_function_or_string
-            == "VIA_CUSTOM_HEADER"  # TODO: add case when this is a function
+            anti_csrf_check is not False and
+            isinstance(self.config.anti_csrf_function_or_string, str) and
+            self.config.anti_csrf_function_or_string == "VIA_CUSTOM_HEADER"
         ):
             raise Exception(
                 "Since the anti-csrf mode is VIA_CUSTOM_HEADER getSession can't check the CSRF token. Please either use VIA_TOKEN or set anti_csrf_check to false"
@@ -283,6 +283,7 @@ async def refresh_session(
     ) -> SessionContainer:
         if (
             disable_anti_csrf is not True
+            and isinstance(self.config.anti_csrf_function_or_string, str)
             and self.config.anti_csrf_function_or_string == "VIA_CUSTOM_HEADER"
         ):
             raise Exception(