Add errors fast api

[arash77]

What did you do?

• Remove 422 Validation error response
• Add 400 Bad request error response
• Create MessageExceptionModel and ValidationErrorModel for the schema of error responses

Why did you make this change?

The Validation error should be replaced by the Bad request error as it is not the real model that is returning.

How to test the changes?

• I've included appropriate automated tests.
• This is a refactoring of components with existing test coverage.
• Instructions for manual testing are as follows:
  1. [add testing steps and prerequisites here if you didn't write automated tests covering all your changes]

License

• I agree to license these and all my past contributions to the core galaxy codebase under the MIT license.

[davelopez]

It seems the 422 is still getting generated in the resulting schema so remove_422 doesn't seem to work as expected. We could keep the 422 as a validation-specific error though given the response data is in the format we want and adapt the client error handling to support it. What do others think about this?

Have a look at https://fastapi.tiangolo.com/tutorial/handling-errors/#override-request-validation-exceptions and this discussion tiangolo/fastapi#9061 if you haven't already, maybe there is an interesting solution there.