plotSlice function: minor fix for empty variables option

[SimonaFa]

No description provided.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 53.04%. Comparing base (57817d7) to head (29ecc10).
⚠️ Report is 1 commits behind head on dev.

Additional details and impacted files

@@            Coverage Diff             @@
##              dev     #859      +/-   ##
==========================================
- Coverage   53.06%   53.04%   -0.03%     
==========================================
  Files         307      307              
  Lines       19813    19812       -1     
==========================================
- Hits        10514    10509       -5     
- Misses       9299     9303       +4     

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[github-actions]

Test Results

  3 files  ±0    3 suites  ±0   42m 40s ⏱️ -2s
288 tests ±0  288 ✅ ±0  0 💤 ±0  0 ❌ ±0 
960 runs  ±0  955 ✅ ±0  5 💤 ±0  0 ❌ ±0 

Results for commit 29ecc10. ± Comparison against base commit 57817d7.

♻️ This comment has been updated with latest results.