We recently reported that there is a bug in Office for the Mac 2016 15.20 release that causes all add-ins to crash Word when you quit Word without opening or editing a document. The same thing happens with Excel.
The good news is that the 15.21 update for Office 2016 for the Mac fixes the crashing problem. We have tested it in both Word and Excel.
The 15.21 update will be released publicly on 4/22/2016 and is available now if you sign up to be an “Insider”. You can join the “Insider” group by checking the Insider box on the Microsoft Auto Update dialog that opens when you click “Check for Updates”.