Last modified: 2010-05-15 16:03:13 UTC
[[MediaWiki:Userinvalidcssjstitle]] introduced in bug 4535 is not shown on preview. This means that users with "Show preview on first edit" option will never see this warning.
Removed the preview condition in r41339 for usercssjsyoucanpreview and userinvalidcssjstitle.
Hmm, I suspect that [[mediawiki:usercssjsyoucanpreview]] will now clash with another message [[mediawiki:usercsspreview]].
You're right, it would if usercsspreview was not disabled for unknown reason. Investigating why.
Enabled again in r41346.