Used pure resolver for errors field in custom mutation payloads

[glen-84]

Summary of the changes (Less than 80 chars)

• Used pure resolver for errors field in custom mutation payloads.

Closes #7660

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 73.95%. Comparing base (a9f442c) to head (27eee9b).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7691      +/-   ##
==========================================
+ Coverage   73.94%   73.95%   +0.01%     
==========================================
  Files        2916     2916              
  Lines      151060   151060              
  Branches    17548    17548              
==========================================
+ Hits       111696   111715      +19     
+ Misses      33511    33493      -18     
+ Partials     5853     5852       -1     

Flag	Coverage Δ
unittests	73.95% <ø> (+0.01%)	⬆️

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