❗️A word on errors 😱

We do not create tracks with (willful) errors, so if you find an error that is most likely to do with:

• a Javascript syntax error - files used but not required, unknown variables, parenthesis () not closed, curlies {} not closed, etc

• comparison between things that aren't the same, usually found in tests - hello is not the same as hello - the latter has an extra space which human eyes find difficult to spot but not a computer!

• asynchronous errors - things are executed before or after we expect them to

• specific API errors - there are errors thrown by node express which are specific to the way we interact with its API, either in test or human, format

The repo you can clone for this project has no errors at the time of writing. You should be able to interact with the API via `npm start` and Postman and run tests with none failing by `npm t`

• Please take a systematic approach and don't write so much code, either in implementation or tests, that you don't know which one might be causing trouble.

• Every time you have changed implementation and/or tests as we are in a "neutral" status (no errors, all tests passing) don't forget to commit/push to Github. This might come in handy if you ever need to go back to a place where you know everything was 👍

• Reading / interpreting error messages are the bread and butter of developer work life. When we start learning programming it's easy to think that debugging "errors" is a waste of time or, time badly spent, time that we could be using to build things. This is a not very accurate perception vs reality - developers solve problems for a living, either by chasing errors, building things, or both.

• Do what good developers do - the moment we feel frustration rising it's time to ask for help.

• Below there's a few unexpected errors we found while writing the solution branch for this track.

1 - Invalid use of NULL value

If you're like me and interact with your API as you build it there might come a time when you get this error when:

• you're running your express server
• you've just updated one (or more) of your model fields to not accepts NULL type fields

This happens because you might have data in your database that no longer matches your schema definition - you might have changed a schema that no longer allows NULL as a value for a field

➡️ How to fix it?

By deleting the (now) offending records in the database.

Hold on, what if "offending records" numbers were in the thousands? We would never recommend deleting data or records unless they're in the context of a track or example.

In a real life example we would probably need to negotiate a database migration (also talk to your nearest Senior Developer or Solutions Architect 😅 )

2 - Cannot set headers after they're sent to the client

Most times we forget to explicitly return res.send() from controllers, or we do not have an {else} logic in a controller. This means we send a second header (read response after one has been already sent. Remember express is only happy with ONE response to a request.

➡️ How to fix it?

Make sure your controller is returning one single response to the current scenario.