Add --debugger global option With this option, hg will drop into the Python debugger on execution. Running 'continue' will execute normally, and the debugger will be reinvoked if an exception is raised.

#!/bin/sh

hg init

echo "Is there an error message when trying to diff non-existing files?"
hg diff not found

echo "Is there an error message when trying to add non-existing files?"
hg add not found