This doesn't work for me with RStudio v1.1.456
I've set
Debug/On Error/Break
in code and also
Tools/Global options/ unchecked 'Use debug error handler only when my code contains errors'
and whilst it does open up the deeply nested file (not my code) where the crash occurs it doesn't give me a line number for the offending line in my code.
I've been successfully getting line numbers for my errors since 1982 so it's frustrating that they seem so elusive in RStudio.
Surely it must be possible somehow?