When I'm trying to translate the es.wiki article AC/DC to Catalan, I get a JS error on ext.cx.source.filter.js line 114:
if ( mappings.parameters[ key ] !== undefined ) {
(Translating AC/DC is broken in general because of the slash in the title; it's a separate issue that is fixed in https://gerrit.wikimedia.org/r/#/c/147891/ .)
Version: unspecified
Severity: normal