I am not sure, if this is a bug in FlaggedRevs or Scribunto, but there are not playing good together.
Going to a stable version of a module gives you a page without Geshi highlighting and with script errors.
Compare these pages:
https://de.wikipedia.org/wiki/Modul:DemoArgs?stable=1
https://de.wikipedia.org/wiki/Modul:DemoArgs?stable=0
Version: unspecified
Severity: normal
It appears to be a bug in FlaggedRevs, in that it just assumes page text is wikitext when displaying the stable version rather than using ContentHandler to determine how the page is to be displayed.
Adjusting bug title accordingly.
stable=1 is only a way to say FlaggedRevs it should show the stable version across user settings (on de.wp anonym user always get stable version, loggedin user get per default the unstable version, but can change it in preferences to the stable, so it is easier to link with stable= in the url instead of saying, some one have to log in to see the difference)
Related URL: https://gerrit.wikimedia.org/r/66893 (Gerrit Change I1cb3a83426cfa9db962e6e8cef06cc32b8713501)
Is now live on de.wp and it looks good (pages needs a purge, but that is okay)
Thanks.