fix out of range access, minor performance improvement (0.27-maintenance backport)

[kevinbackhouse]

This is a backport of #1918. Mergify didn't work.

[codecov]

Codecov Report

Merging #1925 (b8daefe) into 0.27-maintenance (b669a9d) will not change coverage.
The diff coverage is 0.00%.

❗ Current head b8daefe differs from pull request most recent head d853f14. Consider uploading reports for the commit d853f14 to get more accurate results

@@                Coverage Diff                @@
##           0.27-maintenance    #1925   +/-   ##
=================================================
  Coverage             46.30%   46.30%           
=================================================
  Files                   146      146           
  Lines                 22948    22948           
  Branches              11781    11781           
=================================================
  Hits                  10626    10626           
  Misses                 6707     6707           
  Partials               5615     5615           

Impacted Files	Coverage Δ
src/tags_int.cpp	54.54% <0.00%> (ø)

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[kevinbackhouse]

I don't understand why the codecov check is failing. I am very sure that the new tests cover every branch of the new code.

[clanmills]

@kevinbackhouse As always, thank you for working on this.

[clanmills]

@kevinbackhouse As always, thank you for working on this.