fix(sdk): optional chain getSpotMarketAccountAndSlot return in DriftClient (closes #2137)

[cryptomotifs]

Summary

Closes #2137.

getSpotMarketAccount and forceGetSpotMarketAccount access .data on the return value of accountSubscriber.getSpotMarketAccountAndSlot(marketIndex) without first checking the `accountAndSlot` shape. When the subscriber hasn't yet seen the account (or the market index isn't known), the subscriber returns `undefined` and the unguarded `.data` access throws `TypeError: Cannot read properties of undefined (reading 'data')` at runtime.

Both methods are already typed as `... | undefined`, so propagating `undefined` via optional chaining is consistent with the public contract.

Diff

`sdk/src/driftClient.ts` — 4 additions, 2 deletions.

```diff
public getSpotMarketAccount(
marketIndex: number
): SpotMarketAccount | undefined {

•   return this.accountSubscriber.getSpotMarketAccountAndSlot(marketIndex).data;
  

•   return this.accountSubscriber.getSpotMarketAccountAndSlot(marketIndex)
  

•   	?.data;
  

  }

  public async forceGetSpotMarketAccount(
  marketIndex: number
  ): Promise<SpotMarketAccount | undefined> {
  await this.accountSubscriber.fetch();

•   return this.accountSubscriber.getSpotMarketAccountAndSlot(marketIndex).data;
  

•   return this.accountSubscriber.getSpotMarketAccountAndSlot(marketIndex)
  

•   	?.data;
  

  }
  ```

Test plan

• Type-checks: return type already `SpotMarketAccount | undefined`; `?.data` preserves it.
• CI: existing test suite should pass unchanged (no new code paths, behavior strictly safer).
• No call sites need to change — all existing callers already handle `undefined` since the typed signature is unchanged.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Improved resilience of spot market account lookups to gracefully handle missing subscriber data, preventing errors when data is unavailable and returning undefined instead of throwing exceptions.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: a0a12aaa-8561-434c-afd0-83cd71a593dd

📥 Commits

Reviewing files that changed from the base of the PR and between 0ae3e3b and 5fb992e.

📒 Files selected for processing (1)

• sdk/src/driftClient.ts

---

Walkthrough

Updates DriftClient spot-market account accessor methods to use optional chaining when accessing subscriber data, preventing runtime errors when getSpotMarketAccountAndSlot returns no result.

Changes

Cohort / File(s)	Summary
Spot Market Account Accessors sdk/src/driftClient.ts	Added optional chaining (?.data) to getSpotMarketAccount and forceGetSpotMarketAccount methods to safely handle cases where subscriber data is unavailable, returning undefined instead of throwing.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~3 minutes

Poem

🐰 A careful hop through data streams,
With question marks in defensive schemes,
No crash when subscribers fade to nil,
Just gentle undefined—graceful still! ✨

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically describes the main change: adding optional chaining to getSpotMarketAccountAndSlot return in DriftClient.
Linked Issues check	✅ Passed	The pull request fully implements the requirement from issue #2137 by adding optional chaining to both getSpotMarketAccount and forceGetSpotMarketAccount methods.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to the requirements in issue #2137; no extraneous modifications are present.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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