When undefined is applied to onError, defaultOptions.mutations.onError does not work.

[mitchell-up]

Problem

I'd like to make a custom hook with useMutation that can receive onError function.

example like below

const useLogin = (onError?) => {
 return useMutation({
    mutationFn: (signInInfos: SignInInfos) => fetchSignIn(signInInfos),
    onError: onError,
    meta: {
      showToast: true,
    },
  })
}

I also set defaultOptions for mutations.

new QueryClient({
  defaultOptions: {
    // ...
    mutations: {
      onError(error) {
        if (isHttpError(error)) {
          defaultErrorHandlers[error.type](error)
        }
      },
    },
  },
}),

I wanted defaultOptions's onError to work if useLogin didn't recevie an onError callback.
But if it didn't receive the onError, defaultOptions's onError was also not fired.
I think that's why undefined value in the onError option might be overriding the defaultOptions.

My Solution

So I should defaultOptions to onError manually for useMutaion options.

const useLogin = (onError?) => {
  const queryClient = useQueryClient()
  const defaultOptions = queryClient.getDefaultOptions().mutations

  return useMutation({
    mutationFn: (signInInfos: SignInInfos) => fetchSignIn(signInInfos),
    onError: onError || defaultOptions.onError,
    meta: {
      showToast: true,
    },
  })
}

Is it a best solution? or please let me know better approach.