A mobile extension is essentially a panel.
So if you load the same code into a panel you can test it via that route instead and trace the error.
Or use the onError to log helper JS function issues Extensions Reference | Twitch Developers
or try/catch or other frontend JS error logging solutions.
Then collate the error and use fetch to relay it to a server for logging.
At this time and to my knowledge you can’t “connect” to a phone session via remote to access the console log.
And Twitch itself won’t have kep logs for you to access.
So when you say found an error what did you find?