[projmgr] Fix optional empty layer report

[spcaipers-arm]

Address #1873

[github-actions]

Test Results

    3 files     18 suites   8m 21s ⏱️
  376 tests   376 ✅ 0 💤 0 ❌
1 128 runs  1 128 ✅ 0 💤 0 ❌

Results for commit f97fd46.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 64.95%. Comparing base (8422a81) to head (f97fd46).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1874      +/-   ##
==========================================
- Coverage   64.96%   64.95%   -0.01%     
==========================================
  Files         163      163              
  Lines       34587    34589       +2     
  Branches    20065    20067       +2     
==========================================
  Hits        22468    22468              
- Misses       7960     7961       +1     
- Partials     4159     4160       +1     

Flag	Coverage Δ
projmgr-cov	81.66% <100.00%> (-0.02%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
tools/projmgr/src/ProjMgrWorker.cpp	87.69% <100.00%> (+<0.01%)	⬆️

... and 1 file with indirect coverage changes