fix: set Transaction.to to zero address for contract-creation txs

[rickstaa]

Problem

The subgraph halts on any contract-creation transaction that emits a protocol event. On 2026-07-18 this froze Arbitrum One at block 485100964; all 9 indexers report health: failed with missing value for non-nullable field 'to'. See #243.

Root cause

createOrLoadTransactionFromEvent (utils/helpers.ts) skips tx.to when event.transaction.to is null, but Transaction.to is String! (non-nullable). Contract-creation txs have a null to, so graph-node aborts deterministically.

Fix

Default tx.to to the zero address (EMPTY_ADDRESS) when the tx has no recipient. Keeps the schema non-nullable — no downstream/type changes.

Testing

yarn codegen and yarn build pass.

Deployment

Redeploy and graft from block 485100964 (last good block) so indexers resume instead of full-resyncing. Republish so subgraph FE63… points at the fixed deployment.

Fixes #243

🤖 Generated with Claude Code
https://claude.ai/code/session_01JoKwkmU3jMU6DMGoTcCKRe

Summary by CodeRabbit

• Bug Fixes
  • Improved handling of contract-creation transactions by assigning a default empty address when no recipient address is available.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 36f5fe04-cec0-448a-af3e-a0d37894e578

📥 Commits

Reviewing files that changed from the base of the PR and between 2eac27f and c5ddb1d.

📒 Files selected for processing (1)

• utils/helpers.ts

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📝 Walkthrough

Walkthrough

The transaction loading helper now defaults Transaction.to to EMPTY_ADDRESS for contract-creation transactions where the event transaction has no recipient.

Changes

Transaction recipient handling

Layer / File(s)	Summary
Default missing transaction recipients utils/helpers.ts	createOrLoadTransactionFromEvent assigns EMPTY_ADDRESS.toHex() when event.transaction.to is absent and preserves the existing recipient mapping otherwise.

Estimated code review effort: 1 (Trivial) | ~2 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly describes the main code change: defaulting Transaction.to to the zero address for contract-creation transactions.
Description check	✅ Passed	The description includes the problem, root cause, fix, testing, deployment context, and links the issue being fixed.
Linked Issues check	✅ Passed	The change satisfies #243 by preventing null Transaction.to values with an EMPTY_ADDRESS fallback for contract-creation txs.
Out of Scope Changes check	✅ Passed	The summary shows a focused helper change with no unrelated code modifications.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/transaction-to-contract-creation

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[github-actions]

🚀 Subgraph Studio preview deployed

Item	Details
Version label	pr-244-c7f08f9-29698352733
Query endpoint	https://api.studio.thegraph.com/query/31909/livepeer-ci/pr-244-c7f08f9-29698352733

curl -H 'Content-Type: application/json' \
  -d '{"query":"{ protocol(id: \"0\") { inflation } }"}' \
  https://api.studio.thegraph.com/query/31909/livepeer-ci/pr-244-c7f08f9-29698352733

[rickstaa]

Closed in favor of #245