Stack trace
Also called Backtrace, Traceback
What a crash leaves behind: the error message, then every function that was running at that moment, newest first, each with a file and a line. It is a map from where it blew up back to where it started.
It is the most precise bug report you will ever get, and it's free. Give an agent the whole thing, not your summary of it. Then check its story against the trace: if it blames a function that isn't there, it is guessing.
Say it to your agent
“Here is the full stack trace. Start from the top frame that is in our code, open that file at that line, and tell me which value was wrong there and where it came from, before you propose any fix.”