Create different error messages

[josee-sabourin]

What is the issue and why is it an issue?

Currently it seems the only error the validator throws when it is unable to process a feed is "Sorry, this version is not yet implemented or not detectable !", this can be confusing when issues are not related to versioning.

Please describe some potential solutions you have considered (even if they aren’t related to GBFS).

I suggest adding a variety of different error messages for various situations like:

• when a feed has a 404 or 502 error
• blocked user-agent (see issue #90)
• etc.

Please feel free to use this thread to add more ideas for error messages.

[richfab]

Examples of error messages:

• "404 error while trying to retrieve the feed."
• "The feed is not a JSON file."