I have cmn on my userpage. When I click the pen button, I get this because cmn is not available.
<div data-caption-languages="en,cmn,de,yue,zh" class="filepage-mediainfo-entitytermsview oo-ui-layout oo-ui-panelLayout oo-ui-panelLayout-framed oo-ui-pendingElement-pending">
Unsupported babelcodes should be ignored to avoid this I guess?