Bugfix: fix KeyError when metadata raising an MetadataInvalidError.

[MooooCat]

Description

Motivation and Context

How has this been tested?

Types of changes

• Maintenance (no change in code, maintain the project's CI, docs, etc.)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[codecov-commenter]

Codecov Report

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

Comparison is base (ff2022b) 80.26% compared to head (3535fb9) 80.26%.

Files	Patch %	Lines
sdgx/data_models/metadata.py	0.00%	1 Missing ⚠️

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Additional details and impacted files

@@           Coverage Diff           @@
##             main     #134   +/-   ##
=======================================
  Coverage   80.26%   80.26%           
=======================================
  Files          66       66           
  Lines        2975     2975           
=======================================
  Hits         2388     2388           
  Misses        587      587           

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