We should improve the error when a wiki already exisits and CreateWiki attempts to create it.
Currently, errors like:
[ddac331a9a76ed66c8b91342] 2019-07-23 06:43:21: Fatal exception of type "MWException" (to us)
and
MWException from line 75 of /srv/mediawiki/w/extensions/CreateWiki/includes/WikiManager.php: Wiki 'mscwiki' already exists (in logs)
or
[9faf7bdfd927c35693063d0a] 2019-07-22 14:09:52: Fatal exception of type "MWException" (to us)
and
2019-07-22 14:09:52 mw2 metawiki: [9faf7bdfd927c35693063d0a] /wiki/Special:RequestWikiQueue/8740 MWException from line 75 of /srv/mediawiki/w/extensions/CreateWiki/includes/WikiManager.php: Wiki 'windows95wikiwiki' already exists (in the logs)
We should probably put an error up like 'Wiki creation of xxwiki failed as the wiki already exisits to prevent increased workload on Site Reliability Engineering when these errors are caused following issues like 504 errors where the creator has to refresh the browser to recover everything then finds the above errors when it loads