Librem 5 freeze with Pat

I tried using Pat with Librem Phone (Pat lets hams use Amateur radio Winlink gateways to send a Winlink message).
I compiled Pat and built a little utility to set up the serial port correctly if you want to connect to TNC rather than the internet:

However when I use the Pat http interface to go to localhost:8080 and compose a message, and hit “post” button, it always freezes the whole browser.

I don’t know how one connects the Librem phone debugger the way you would to a desktop Chrome or Safari for iOS, is there a good way to debug what freezes the whole Librem web browser? because this seems to be a reliable way to get the browser into a frozen state.

See also

I am not an expert in this field, but perhaps if you launch the browser from the terminal?