It seems we usually don't return right away, but do something like

const response = await callServerEndpoint('verify_invite_link', request);
return {
  field: response.field;
  ...
};

I'm not sure why, probably so that the potential type errors are thrown from here, and not later. Can you follow the same pattern or explain why it's not needed please?

You're right. The purpose of this pattern is that the result of callServerEndpoint could have more fields, e.g. success. We don't want these fields further down.