fix: handle properly 400s and 500s [AIRT-47]

[pkey]

❓ What does this change do?

If it's a 400, pass it through and display the message that came from the backend. This allows for more flexibility in the future and us defining errors in the backend rather than releasing the client code each time.

In this particular case, it enables us seeing the concurrent requests error:

[snyk-io]

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