With the release of Firefox 47.0.1, Mozilla appear to have tightened up some of the syntax checking for browser extensions. Unfortunately, this has brought to light a problem with the FindIT extension which means that the extension will fail to load in Firefox 47.0.1. We are aware of the problem and will update the extension on addons.mozilla.org as soon as possible. Once the update is published, the FindIT extension should update automatically without requiring any reinstallation of FindIT. In the interim, you may continue to use FindIT with another web browser.
I will update this thread once we have the fix published.
FindIT Product Manager