Note that Scribunto provides the backtrace when you click the error that is output in the page, assuming you have JavaScript enabled:

Inside Lua, if you're catching errors you can use xpcall() and use debug.traceback() inside the handler (or as the handler) to get the trace.

Generalizing the message itself is not all that likely: you'd need mw.text.trim() to pre-validate its parameters before calling gsub() and raise its own errors, and the same (with different validation code) for each other function. The more you try to validate against all possible errors, the more complex and slow that validation becomes.