Tanstack Start Integration?

[adam-enition]

Is the tanstack start integration actually working for anyone? This could be a skill issue but I'm struggling to get it working as detailed in the docs. I have the exact setup as the tanstack form start example - https://tanstack.com/form/latest/docs/framework/react/examples/tanstack-start

First issue is in the handleForm code:

export const handleForm = createServerFn({ method: 'POST' })
  .inputValidator((data: unknown) => {
    if (!(data instanceof FormData)) {
      throw new Error('Invalid form data');
    }
    return data;
  })
  .handler(async (ctx) => {
    try {
      const validatedData = await serverValidate(ctx.data);
      console.log('validatedData', validatedData);
    }
    catch (e) {
      if (e instanceof ServerValidateError) { // <- Here, e is showing a ServerValidateError, but not an instanceof??
        return e.response;
      }

      setResponseStatus(500);
      return 'There was an internal error';
    }

    return 'Form has validated successfully';
  });

e.response is never returned as e does not appear to be a real instance of ServerValidateError which I am importing from @tanstack/react-form-start

If I change the above to:

export const handleForm = createServerFn({ method: 'POST' })
  .inputValidator((data: unknown) => {
    if (!(data instanceof FormData)) {
      throw new Error('Invalid form data');
    }
    return data;
  })
  .handler(async (ctx) => {
    try {
      const validatedData = await serverValidate(ctx.data);
      console.log('validatedData', validatedData);
    }
    catch (e) {
      if (e.name === 'ServerValidateError') { // <- Now works
        return e.response;
      }

      setResponseStatus(500);
      return 'There was an internal error';
    }

    return 'Form has validated successfully';
  });

This now works and e.response is correctly returned. However this then brings me to the next issues. Even thought I have transform set on useForm, the state doesn't seem to be set correctly. So for this:

export const Route = createFileRoute('/form-test')({
  component: Home,
  loader: async () => ({
    state: await getFormDataFromServer(),
  }),
});

function Home() {
  const { state } = Route.useLoaderData();

  const form = useForm({
    ...formOpts,
    transform: useTransform(baseForm => mergeForm(baseForm, state), [state]), // <-- Here
  });

  const formErrors = useStore(form.store, formState => formState.errors);

  return (
    <form action={handleForm.url} method="post" encType="multipart/form-data">
      {formErrors.map(error => (
        <p key={error as never as string}>{error}</p>
      ))}

      <form.Field
        name="age"
        validators={{
          onChange: ({ value }) =>
            value < 8 ? 'Client validation: You must be at least 8' : undefined,
        }}
      >
        {(field) => {
          return (
            <div>
              <input
                name="age"
                type="number"
                value={field.state.value}
                onChange={e => field.handleChange(e.target.valueAsNumber)}
              />
              {field.state.meta.errors.map(error => (
                <p key={error as string}>{error}</p>
              ))}
            </div>
          );
        }}
      </form.Field>
      <form.Subscribe
        selector={formState => [formState.canSubmit, formState.isSubmitting]}
      >
        {([canSubmit, isSubmitting]) => (
          <button type="submit" disabled={!canSubmit}>
            {isSubmitting ? '...' : 'Submit'}
          </button>
        )}
      </form.Subscribe>
    </form>
  );
}

The state should be being merged via the call to useTransform(baseForm => mergeForm(baseForm, state), [state]) but that doesn't seem to be the case. E.g. the age field is never populated with that from the state. So if I post an age of 3 for example, I'd expect the validation to fail and the form to load with the value of 3. It doesn't, it just goes back to the defaultValue (0 in the example case).

This is the same for the server validation errors. The errorMap on the form state looks to contain the correct errors, however these do not seem to be propagated to the individual fields.

Am I going mad or does this just not work yet?