On wmf.19 (not in wmf.18) and in betalabs, RecentChanges and Watchlist produce the following console error upon loading
Uncaught TypeError: Cannot read property 'toggle' of undefined
at MwRcfiltersUiFilterTagMultiselectWidget.FilterTagMultiselectWidget.onChangeTags
at MwRcfiltersUiFilterTagMultiselectWidget.OO.EventEmitter.emit
at MwRcfiltersUiFilterTagMultiselectWidget.OO.ui.mixin.GroupElement.clearItemsWith the specific reference to this.emptyFilterMessage.toggle(this.isEmpty());
FilterTagMultiselectWidget.prototype.onChangeTags = function() {
if (this.controller.isInitialized()) {
FilterTagMultiselectWidget.parent.prototype.onChangeTags.call(this);
}
this.emptyFilterMessage.toggle(this.isEmpty());
}