fix: Join validation for multiple keys

[ritchie46]

fixes #15829

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.25%. Comparing base (b6441d0) to head (ce86d87).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #15947      +/-   ##
==========================================
- Coverage   81.25%   81.25%   -0.01%     
==========================================
  Files        1381     1381              
  Lines      176636   176640       +4     
  Branches     3034     3034              
==========================================
+ Hits       143532   143535       +3     
- Misses      32622    32623       +1     
  Partials      482      482              

Flag	Coverage Δ
python	74.69% <100.00%> (+<0.01%)	⬆️
rust	78.38% <100.00%> (-0.01%)	⬇️

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