Stacktrace line numbers in @defcomp Macro

[lrennels]

This most recently came up when I was helping to debug some code for Helen and found that the stacktrace for the missing access uses the macro expansion line numbers, making it cumbersome to hunt down which indexing expression causes a problem. Maybe this is just the way it is, especially without a debugger, but we could brainstorm a way to improve it if possible.

[rjplevin]

A simple one-line fix (for each of run_timestep and init) cures this. See new PR.

[lrennels]

I am reopening this issue per this discussion: https://forum.mimiframework.org/t/improve-missing-data-error-message/96/3 where the error message doesn't seem to be correct ... but it seems we should have solved this here. Talking to Frank to see if the line number was correct.