fix: Transaction list validation

[gsstoykov]

Description:

Adds proper internal validation.

Related issue(s):

Fixes #1274

Notes for reviewer:

Checklist

• Documented (Code comments, README, etc.)
• Tested (unit, integration, etc.)

[github-actions]

Hey @gsstoykov 👋 thanks for the PR!
I'm your friendly PR Helper Bot 🤖 and I'll be riding shotgun on this one, keeping track of your PR's status to help you get it approved and merged.

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PR Checks

✅ DCO Sign-off -- All commits have valid sign-offs. Nice work!

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✅ GPG Signature -- All commits have verified GPG signatures. Locked and loaded!

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✅ Merge Conflicts -- No merge conflicts detected. Smooth sailing!

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✅ Issue Link -- Linked to #1274 (assigned to you).

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🎉 All checks passed! Your PR is ready for review. Great job!

[rwalworth]

LGTM, thanks for addressing the feedback!

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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🟢 Metrics 16 complexity . 32 duplication

Metric	Results
Complexity	16
Duplication	32

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