On the English Wikisource, if math display preferences are set to MathML, this revision: https://en.wikisource.org/w/index.php?title=User:Beleg_T%C3%A2l/Sandbox&oldid=6026384 creates "[61c72485] 2015-12-24 14:38:42: Fatal exception of type "MWException"". If math preferences are set to PNG, it displays correctly.
The issue seems to be identical to T121763, however unlike T121763 this issue occurs even if there is no \binom in a subscript.