test: Dont initialize array in SupertokensSessionError class definition

Author: KShivendu

supertokens_python/recipe/session/exceptions.py

@@ -28,6 +28,8 @@ def raise_token_theft_exception(user_id: str, session_handle: str) -> NoReturn:
 def raise_try_refresh_token_exception(ex: Union[str, Exception]) -> NoReturn:
     if isinstance(ex, SuperTokensError):
         raise ex
+
+    assert isinstance(ex, str)
     raise TryRefreshTokenError(ex) from None
 
 
@@ -40,12 +42,23 @@ def raise_unauthorised_exception(
         response_mutators = []
 
     err = UnauthorisedError(msg, clear_tokens)
-    err.response_mutators.extend(UnauthorisedError.response_mutators)
+    err.extend_response_mutators(response_mutators)
+
     raise err
 
 
 class SuperTokensSessionError(SuperTokensError):
-    response_mutators: List[ResponseMutator] = []
+    def __init__(
+        self, msg: str, response_mutators: Optional[List[ResponseMutator]] = None
+    ):
+        super().__init__(msg)
+        self.response_mutators = response_mutators
+
+    def extend_response_mutators(self, response_mutators: List[ResponseMutator]):
+        if self.response_mutators is None:
+            self.response_mutators = []
+
+        self.response_mutators.extend(response_mutators)
 
 
 class TokenTheftError(SuperTokensSessionError):

supertokens_python/recipe/session/recipe.py

@@ -221,7 +221,10 @@ async def handle_api_request(
     async def handle_error(
         self, request: BaseRequest, err: SuperTokensError, response: BaseResponse
     ) -> BaseResponse:
-        if isinstance(err, SuperTokensSessionError):
+        if (
+            isinstance(err, SuperTokensSessionError)
+            and err.response_mutators is not None
+        ):
             for mutator in err.response_mutators:
                 mutator(response)
 

supertokens_python/recipe/session/session_request_functions.py

@@ -422,7 +422,7 @@ async def refresh_session_in_request(
                     )
                 )
 
-        e.response_mutators.extend(response_mutators)
+        e.extend_response_mutators(response_mutators)
         raise e
 
     log_debug_message(