Error object from useMutation is different from what comes from the server

[ivanSidarau]

Why is the Error object from useMutation different from what comes from the server and how do I fix it?
I have custom hook with this logic:

const unmountRef = useUnmountRef();

  const handledMutationFn =  (...additionalPayload) => {
      const isCallbacksAllowed = !unmountRef.current || !isCallbacksBlockedAfterUnmount;
      const params = payload !== undefined ? [payload] : additionalPayload;

      return mutationFn(...params)
        .then(response => {
          onSuccess && isCallbacksAllowed && onSuccess(response, unmountRef, ...params);

          return processResponse ? processResponse(response, ...params) : response;
        })
        .catch(error => {
          IS_ENV_DEVELOPMENT && console.warn(error);

          console.log('1 err', { error, keysInError: Object.keys(error) }); ------------------------------ 1 log

          onError && isCallbacksAllowed && onError(error, unmountRef, ...params);

          throw new Error(processError ? processError(error, ...params) : error);
        });
    }

  const {
    data,
    mutate,
    error,
    reset,
    isSuccess: loaded,
    isLoading: loading,
  } = useMutation(handledMutationFn);

 console.log('2 err', { error, keysInError: error && Object.keys(error) }); ---------------------------- 2 log

the point is that I get the same error, but useMutation returns me just a string instead of an error!

[TkDodo]

Because you catch the error and create a new Error ?

[ivanSidarau]

I didn't know that the new Error construct can change an error. Thanks for the reply, it prompted me to do some more checking and I found a solution:
throw processError ? new Error(processError(error, ...params)) : error;