The querystrings.js on the [github page](http://bgrins.github.io/devtools-snippets/#querystringvalues) differs slightly from the [source on github](https://github.com/bgrins/devtools-snippets/blob/master/snippets/querystringvalues/querystringvalues.js), and returns an error when run whereas the source does not. Might be worth an update!