What's the best way to troubleshoot user errors?

I’ve managed to get my private app up and running on the community cloud, and shared it with one of my collaborators. Now I would like to ‘alpha’ the app by having a limited number of users try it out. The main point of this is to debug it and try to address any errors the users might get.

What is the best way to manage this process? Is it possible to make it so that the tracebacks from any errors the users might get are automatically sent to me? Also, given that the app involves the user updating their own data, what’s the best/most secure way for the users to send this to me so I can try to replicate and fix the problem?