---
id: TASK-78
title: 'Fix all pre-existing tsc --noEmit errors (10 errors, 5 files)'
status: Done
assignee: []
created_date: '2026-03-02 22:52'
labels:
  - dx
  - typescript
dependencies: []
priority: medium
---

## Description

<!-- SECTION:DESCRIPTION:BEGIN -->
Resolve all 10 TypeScript strict type-check errors reported by `tsc --noEmit`. These were pre-existing issues (not caught by vite build) across 5 files: folk-map-viewer.ts, test-x402.ts, key-derivation.ts, wallet-store.ts, and webauthn.ts. Mostly TS 5.7+ strictness around Uint8Array.buffer returning ArrayBufferLike vs ArrayBuffer at WebCrypto API boundaries.
<!-- SECTION:DESCRIPTION:END -->

## Acceptance Criteria
<!-- AC:BEGIN -->
- [ ] #1 tsc --noEmit reports 0 errors
- [ ] #2 vite build still passes
- [ ] #3 No runtime behavior changes
<!-- AC:END -->

## Final Summary

<!-- SECTION:FINAL_SUMMARY:BEGIN -->
Fixed all 10 pre-existing `tsc --noEmit` errors across 5 files:

- **folk-map-viewer.ts** (1): Removed explicit return type annotation, let TS infer
- **test-x402.ts** (1): Cast `account as any` (test script, `readContract` not called at runtime)
- **key-derivation.ts** (5): Cast `as BufferSource` / `as ArrayBuffer` at WebCrypto API boundaries (TS 5.7+ Uint8Array.buffer strictness)
- **wallet-store.ts** (1): Cast `.buffer as ArrayBuffer`
- **webauthn.ts** (2): Cast PRF output `as ArrayBuffer | undefined`

Commit: 33156cc. Deployed to production.
<!-- SECTION:FINAL_SUMMARY:END -->
