Check for existing of avatar_urls array before trying to return the avatar img part of user autocomplete fragment

[glendaviesnz]

Description

Currently the user mention autocomplete fails if the site is returning false for get_option( 'show_avatars' ).

Fixes #18258

How has this been tested?

Tested manually by toggling show_avatars
Added simple unit test to ensure return of user details fragment doesn't fail if avatars array not set

Screenshots

Before:

After:

Types of changes

Made the packages/editor/src/components/autocompleters/user.js getOptionLabel method defensive to check for existence of the avatar url before trying to set img tag

Checklist:

• [ X ] My code is tested.
• [ X ] My code follows the WordPress code style.

[kwight]

If I understand correctly, show_avatars is related to showing avatars for commenters on the front-end of the site – I'm not sure we have the same expectation when using autocomplete. Another option we have is to treat the autocomplete the same as the username in the top right corner; when show_avatars is off, a small generic icon is still used:

[glendaviesnz]

Another option we have is to treat the autocomplete the same as the username in the top right corner; when show_avatars is off, a small generic icon is still used:

I have modified the PR to use this approach:

[glendaviesnz]

@talldan, if you could cast your eyes over this when you get a chance that would be great. The immediate need for this fix has gone, as the issue with missing avatars we had was resolved, but would be good to get this merged in to prevent the same issue if there is ever a regression with the avatars.

[glendaviesnz]

@talldan, @youknowriad - would be good to get this one either merged or closed if you have a chance to look at it in the near future. Thanks.

[youknowriad]

I haven't tested this but code-wise this is looking good to me.

[glendaviesnz]

Rebased and did some more manually testing of this, all still works as advertised so will go ahead and merge.