Handle errors in requests

[LucasLobo]

Errors are not being handled which crashes the application.

getAlias:

Notice how:

• 404 is a user error, which means it can be forwarded normally
• Other errors (every time data.statusCode is defined in the forwardEmail api) which are not handled are considered a server error (500).
• Otherwise 200 is returned

All other methods should follow the same principle.