better validation errors, dont include all errors (#290)

## Why

previously, if you accidentally sent the wrong payload (e.g. mismatched
service versions), you would get `expected requestData or control
payload` which is a very unclear message given that you did provide
`requestData`, its just wrong

## What changed

- tweaked the error message to be more straightforward
- include extras in the invalid message back to the client

<!-- Describe the changes you made in this pull request or pointers for
the reviewer -->

## Versioning

- [ ] Breaking protocol change
- [ ] Breaking ts/js API change

<!-- Kind reminder to add tests and updated documentation if needed -->

Author: jackyzha0