When attempting to add a category using Visual Editor it fails to search for the appropriate category as I type in the text. As a result I cannot select the category or add it.
Looking in the console I see that I get a TypeError: this.getTagName each time it attempts to search for matching categories.
To reproduce go to e.g. wmse:User:André_Costa_(WMSE)/category_bug
Click page alternatives → categories → enter "Wikispeech 2016"