In this picture we can see to Mwoauthdatastore-request-token-already-requested shows html taqs instead of using it:
It shouldn't be <a class="external" href="-{R|https://www.mediawiki.org/wiki/Help:OAuth/Errors#E009}-">E009</a>, but it should be E009.
It shouldn't be <a class="external" href="-{R|https://www.mediawiki.org/wiki/Help:OAuth/Errors#E009}-">E009</a>
It isn't; judging from the color a part of it does get turned into a link, so the raw HTML must be something like <a class="external" href="<a href="???">-{R|https://www.mediawiki.org/wiki/Help:OAuth/Errors#E009}-</a>">E009</a> No idea what's going on there. Presumably this is Serbian and the -{R thing is some language converter code?