Add check to avoid runtime error and add tests for go/mysql/fastparse

[beingnoble03]

Description

This PR adds a check to avoid runtime error and adds tests for go/mysql/fastparse

Related Issue(s)

Fixes part of #14931

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

Deployment Notes

[vitess-bot]

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (6f48aba) 47.30% compared to head (d55d6bf) 47.34%.
Report is 9 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #15000      +/-   ##
==========================================
+ Coverage   47.30%   47.34%   +0.04%     
==========================================
  Files        1141     1144       +3     
  Lines      238965   238995      +30     
==========================================
+ Hits       113040   113163     +123     
+ Misses     117325   117243      -82     
+ Partials     8600     8589      -11     

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[frouioui]

LGTM! thank you 🙏🏻