In my two years of usage, every time this has happened, there was already an update waiting for me in the main menu.

I've only been using SmartTube about a year and YT changes have caused it to (partly) break only once in that time and all I needed to do was update to the latest version (which is one-click inside the app itself) and it was fixed. Also, I was a several months out of date on versions and the fixed version had been available for weeks already.