fix: Raise if apply returns different types

[ritchie46]

fixes #20104

[codecov]

Codecov Report

Attention: Patch coverage is 73.46939% with 13 lines in your changes missing coverage. Please review.

Project coverage is 79.63%. Comparing base (cbc0ea0) to head (e88984c).
Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
...polars-core/src/chunked_array/from_iterator_par.rs	69.76%	13 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #20168      +/-   ##
==========================================
+ Coverage   79.58%   79.63%   +0.04%     
==========================================
  Files        1564     1564              
  Lines      217475   217480       +5     
  Branches     2472     2473       +1     
==========================================
+ Hits       173070   173182     +112     
+ Misses      43837    43729     -108     
- Partials      568      569       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.