Add comment in test to prevent php8.1 compat issue

[siad007]

Without a comment pdepend will raise an error.

preg_match_all(): Passing null to parameter #2 ($subject) of type string is deprecated

[codecov]

Codecov Report

Merging #1562 (18e9f46) into main (8212a11) will not change coverage.
The diff coverage is n/a.

❗ Current head 18e9f46 differs from pull request most recent head 436ce79. Consider uploading reports for the commit 436ce79 to get more accurate results

@@            Coverage Diff            @@
##               main    #1562   +/-   ##
=========================================
  Coverage     55.96%   55.96%           
  Complexity     6913     6913           
=========================================
  Files           355      355           
  Lines         16739    16739           
=========================================
  Hits           9368     9368           
  Misses         7371     7371           

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