Add dvs as real to optimization problem

[eirikurj]

Purpose

DVs should be real before adding to pyOptSparse, otherwise implicit casting might fail and hang the optimization process, as happens with SLSQP described in mdolab/MACH-Aero#96. This was initially caused by a change in pyOptSparse (see this PR and comment).

This PR addresses this issue. Additionally, made a small refactor to reduce multiple raise Error calls.

Ideally, DVGeo DVs should not be allocated by default as complex, but cast as needed. This is however a more fundamental change. This PR is intended to get SLSQP working again quickly, as it has been broken for months, and allow SLSQP MACH-Aero integration tests to be added.

Expected time until merged

ASAP as MACH-Aero and SLSQP do not work past pyOptSparse 2.10

Type of change

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (non-backwards-compatible fix or feature)
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Documentation update
• Maintenance update
• Other (please describe)

Testing

Run MACH-Aero tests

Checklist

• I have run flake8 and black to make sure the Python code adheres to PEP-8 and is consistently formatted
• I have formatted the Fortran code with fprettify or C/C++ code with clang-format as applicable
• I have run unit and regression tests which pass locally with my changes
• I have added new tests that prove my fix is effective or that my feature works
• I have added necessary documentation

[codecov]

Codecov Report

Attention: 2 lines in your changes are missing coverage. Please review.

Comparison is base (86caa3b) 65.30% compared to head (8e8cf55) 65.32%.

Files	Patch %	Lines
pygeo/parameterization/DVGeo.py	75.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #236      +/-   ##
==========================================
+ Coverage   65.30%   65.32%   +0.02%     
==========================================
  Files          47       47              
  Lines       12122    12121       -1     
==========================================
+ Hits         7916     7918       +2     
+ Misses       4206     4203       -3     

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[marcomangano]

Thanks for fixing this. I agree that we should revisit the way DVs are allocated in pyGeo at a later stage.

[sseraj]

I checked that the MACH-Aero examples now run with SLSQP. Thanks!