tools: fix panic issue in tso bench

[nolouch]

What problem does this PR solve?

Issue Number: Close #8448

What is changed and how does it work?

tools: fix panic issue in tso bench

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
  
  no panic

Release note

None.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.40%. Comparing base (024656b) to head (55c1f75).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8449      +/-   ##
==========================================
+ Coverage   77.31%   77.40%   +0.08%     
==========================================
  Files         472      472              
  Lines       61799    61799              
==========================================
+ Hits        47781    47836      +55     
+ Misses      10441    10393      -48     
+ Partials     3577     3570       -7     

Flag	Coverage Δ
unittests	77.40% <ø> (+0.08%)	⬆️

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: lhy1024, rleungx

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• OWNERS [lhy1024,rleungx]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-07-26 08:06:12.860302253 +0000 UTC m=+1205194.851243723: ☑️ agreed by lhy1024.
• 2024-07-26 08:19:15.690070279 +0000 UTC m=+1205977.681011749: ☑️ agreed by rleungx.

[HuSharp]

/check-issue-triage-complete

[ti-chi-bot]

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