I cannot inject lua into the script I am running or modify it to use pcall. I am using (and must use <Engine>.doString).
I looked through the source code and couldn't find any way to get the error details, it seems that it is just logged to the console and there is no JavaScript end that I can hook into for getting the error, the value is popped off the stack and everything.
In general I need a way to get the error line and message without having to parse the thrown JavaScript <Error>.message property.