Check tracking errors in Google Analytics

1. Put the minified Javascript into a bookmark, starting javascript: (JS manually minified with this free tool)
2. Click the bookmark to load a Query Explorer page with the filters applied

N.B. as it opens in a new tab, may throw a pop-up block error the first time you try -- for ease, I gave permissions for Query Explorer to open pop-ups, then just run from an existing Query Explorer tab.