[Fixes #12651] Wrong extent calculated for empty maps

[giohappy]

Checklist

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 64.16%. Comparing base (677c578) to head (7bddf1b).
Report is 1 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##           master   #12652       +/-   ##
===========================================
+ Coverage   32.84%   64.16%   +31.31%     
===========================================
  Files         889      889               
  Lines       53766    53760        -6     
  Branches     6636     6633        -3     
===========================================
+ Hits        17661    34496    +16835     
+ Misses      35163    17747    -17416     
- Partials      942     1517      +575