Add filename/fieldname to syntax errors for "keyframe" fields

[clemos]

Hi there 👋

This is a small PR to add minimal position info when a syntax error is raised while parsing key frame params.

Example new output:
Error: ''(' was never closed (translation_x@frame#26, line 1)'. Check your schedules/ init values please. Also make sure you don't have a backwards slash in any of your PATHs - use / instead of . Full error message is in your terminal/ cli.

instead of just:
Error: ''(' was never closed (, line 1)'. Check your schedules/ init values please. Also make sure you don't have a backwards slash in any of your PATHs - use / instead of . Full error message is in your terminal/ cli.

It also comes with minor refactoring to lower repetition in animation_key_frames.py

Any comment welcome :)

Also, I was willing to do further cleanup in this part of the code, but IMHO it lacks some unit tests to avoid breaking changes.
Do you have unit tests in place ? If not, do you plan on adding some, and if so how ?
In any case, do you have test cases to share regarding keyframe parsing ?

Thanks for your work :)

[hithereai]

Thanks for the pr! I will look into it soon.

You're welcome to DM me in discord for further discussions on the raised points:
https://discordapp.com/users/hithere

[kabachuha]

Handles not all syntax breakup cases (like 0: (0.34), but a good beginning nevertheless