Well today I did a brad new setup with latest version of ionic and all npm plugins .
but I was not able to replicate the issue with uncaught in promise .
1. Please check : https://prntscr.com/h2lm96 , Can you please share your all project folder along with node_modules in zip format so that I can try to make it run on my machine ?
2. Yes the issue is replicated ,it appears when you start quiz and then leave it then come back to course try sliding through the units . We are working on it to resolve this issue . thanks for reporting it .