More consistent error codes and format

[nortron]

These 3 commits attempt to make the API more consistent in returning JSON errors with non-2xx HTTP error codes.

• When requesting an unknown URL or exceeding rate limits the response is returned as plaintext instead of JSON: https://the-one-api.dev/v2/notreal
  • Both should be addressed by the 1st and 3rd commits
• Error handling in the Book endpoints was not returning a status code so 200 comes back: https://the-one-api.dev/v2/book/123
  • Instead of inserting the 500 status code like the other endpoints currently do I centralized the entire error handling to the final express error handler so if the error message ever needs to change it can happen in one place.
    • Express docs say Starting with Express 5, route handlers and middleware that return a Promise will call next(value) automatically when they reject or throw an error. If this repo is ever ever upgraded to Express 5 (currently on 4.17) or later these new try blocks can be entirely removed, the next() calls will be automatic.

The 4th commit updates a code comment to reflect the latest code.

[MateuszKikmunter]

Looks good to me, good idea with a centralized error handler. 👍
One thing though - can you pls change notFoundResponse to be just Not Found instead of Endpoint does not exist.

[nortron]

@MateuszKikmunter No problem, updated to "Not found" with a lowercase "found" to be consistent with the "Something went wrong" capitalization. Happy to make it all caps if you'd prefer that.

[MateuszKikmunter]

Looks good to me, thanks for taking my suggestions into consideration.

[MateuszKikmunter]

@MateuszKikmunter No problem, updated to "Not found" with a lowercase "found" to be consistent with the "Something went wrong" capitalization. Happy to make it all caps if you'd prefer that.

Thanks, looks good to me, now it needs to be approved by @gitfrosh :)