geant4: Adding warning message for divide by units to add properties …

[sealden89]

…to materials.

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (0a2b1b7) 70.47% compared to head (2c6c771) 70.47%.

Files	Patch %	Lines
src/pyg4ometry/geant4/_Material.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #144      +/-   ##
==========================================
- Coverage   70.47%   70.47%   -0.01%     
==========================================
  Files         144      144              
  Lines       21896    21898       +2     
==========================================
+ Hits        15431    15432       +1     
- Misses       6465     6466       +1     

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[ManuelHu]

But why is this check needed in this generality? Units containing a slash (/) are completely normal and can be used in Geant4, so there should be no warning?

Currently your code even advises an user to use 1/unit - even if the user already did pass 1/unit :)

Or did you intend to search for a leading slash, e.g. to warn if one would pass vunit = "/MeV" (which clearly is invalid)? But then the check is wrong, and should be vunit.find("/") == 0.