Steps to replicate the issue (include links if applicable):
- Visit https://en.wikipedia.beta.wmflabs.org/wiki/Talk:Main_Page
- Report the first comment from User:Medelam
- Select the non emergency flow, or the emergency flow
- Press submit
What happens?:
- An API error (no user facing error message) of {"errorKey":"reportincident-dialog-violator-nonexistent","messageTranslations":{"en":"You must provide an existing username to report."},"httpCode":404,"httpReason":"Not Found"}
What should have happened instead?:
- A user facing error message should be shown for API errors. For the emergency flow, it appears, because there is a username field. The non-emergency flow doesn't have a username field, so no error message is shown.
- We should allow non existing users to be reported. Otherwise, a bad actor could make a harassing comment, then change their name in the wikitext of the talk page to a non existing username, and users would not be able to report the comment with our incident reporting system
Software version (on Special:Version page; skip for WMF-hosted wikis like Wikipedia):
Other information (browser name/version, screenshots, etc.):