fix: add nil guards for Solana tx metadata and safe signature parsing (backport #4550)

[ws4charlie]

Summary

• Backport of fix: add nil guards for Solana tx metadata and safe signature parsing #4550 to release/zetaclient/v38
• Add Meta != nil guard before accessing txResult.Meta.Err in three locations to prevent potential nil pointer dereference
• Replace MustSignatureFromBase58 (panics on invalid input) with SignatureFromBase58 (returns error) in inbound_tracker.go

Test plan

• CI passes

🤖 Generated with Claude Code

---

Note

Low Risk
Small defensive changes that reduce crash risk; behavior changes only for malformed tracker hashes or RPC responses missing Meta.

Overview
Hardens Solana transaction processing by adding Meta != nil guards before checking Meta.Err in inbound filtering, outbound confirmation (CheckFinalizedTx), and outbound tracker reporting to prevent nil-pointer crashes on RPC responses without metadata.

Makes inbound tracker handling resilient to malformed TxHash values by replacing MustSignatureFromBase58 with SignatureFromBase58, logging the parse error, and skipping the bad tracker instead of panicking.

^{Written by Cursor Bugbot for commit 2193592. Configure here.}

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on base/target branches other than the default branch.

🗂️ Base branches to auto review (1)

• develop

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch backport/4550-fix-solana-nil-meta-and-must-signature

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{Bugbot Autofix is OFF. To automatically fix reported issues with Cloud Agents, enable Autofix in the Cursor dashboard.}

Comment @cursor review or bugbot run to trigger another review on this PR

[codecov]

Codecov Report

❌ Patch coverage is 18.18182% with 9 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...taclient/chains/solana/observer/inbound_tracker.go	0.00%	8 Missing ⚠️
.../chains/solana/signer/outbound_tracker_reporter.go	0.00%	1 Missing ⚠️

📢 Thoughts on this report? Let us know!