Check that the string isn't empty (backport #1820)

[mergify]

This is an automatic backport of pull request #1820 done by Mergify.
Cherry-pick of adde00a has failed:

On branch mergify/bp/main/pr-1820
Your branch is ahead of 'origin/main' by 1 commit.
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Changes to be committed:
	modified:   tests/bugfixes/github/test_issue_ghsa_v5g7_46xf_h728.py

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   src/value.cpp

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/github/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

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[codecov]

Codecov Report

Merging #1826 (644aaaa) into main (0eacac6) will increase coverage by 0.01%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##             main    #1826      +/-   ##
==========================================
+ Coverage   60.50%   60.52%   +0.01%     
==========================================
  Files          96       96              
  Lines       18852    18851       -1     
  Branches     9472     9471       -1     
==========================================
+ Hits        11407    11410       +3     
+ Misses       5155     5154       -1     
+ Partials     2290     2287       -3     

Impacted Files	Coverage Δ
src/value.cpp	73.18% <66.66%> (+0.57%)	⬆️

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