Allow for empty 2D wavecal solution in HDU extension of WaveCalib file

[kbwestfall]

As titled.

[profxj]

do it!

[debora-pe]

Thanks @kbwestfall

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

Attention: Patch coverage is 67.32673% with 33 lines in your changes missing coverage. Please review.

Project coverage is 38.48%. Comparing base (8ec2351) to head (b9baa54).
Report is 91 commits behind head on release.

Files	Patch %	Lines
pypeit/utils.py	55.00%	18 Missing ⚠️
pypeit/core/findobj_skymask.py	79.31%	6 Missing ⚠️
pypeit/cache.py	66.66%	2 Missing ⚠️
pypeit/find_objects.py	83.33%	2 Missing ⚠️
pypeit/scripts/show_2dspec.py	0.00%	2 Missing ⚠️
pypeit/core/skysub.py	50.00%	1 Missing ⚠️
pypeit/core/wavecal/autoid.py	0.00%	1 Missing ⚠️
pypeit/scripts/identify.py	0.00%	1 Missing ⚠️

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@             Coverage Diff             @@
##           release    #1825      +/-   ##
===========================================
- Coverage    38.53%   38.48%   -0.05%     
===========================================
  Files          206      207       +1     
  Lines        47992    48151     +159     
===========================================
+ Hits         18494    18532      +38     
- Misses       29498    29619     +121     

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