How to extract signal from almost useless error message

Debugging is not the plan, listing the directions in the order I would touch them if I were debugging is a much more limited action.

It has something to do with line X, but typically not caused by it. Trace often contains the attribute names at some intermediate steps, and these are often (unfortunately not always) more telling (unfortunately still not direct pointers, but closer)

The pragmatical part is that there are sometimes some relatively easy signs in the full trace to determine which part of the expression to recheck.