Issue Review: cloudflare/workers-sdk#9919

Summary

Wrangler crashes when processing truncated/incomplete stack traces in worker stderr due to sourcemap processing expecting complete line:column format.

Findings

• Created: 2025-07-10
• Updated: 2025-07-14
• Version: 4.20.0 → 4.60.0 (current)
• Component: wrangler (sourcemap support in dev mode)
• Labels: bug
• Comments: 4 (includes maintainer acknowledgment)

Key Evidence

• Reproduction confirmed: Bug reproduces with latest wrangler 4.60.0 using reporter's reproduction code
• Error: column must be greater than or equal to 0 (columns start at column 0)
• Root cause: getSourceMappedString function doesn't handle truncated stack traces where the line:column format is incomplete
• Maintainer response: @petebacondarwin acknowledged the issue (2025-07-14) and discussed potential fixes:
  • Debouncing chunk handling (problematic - may combine multiple exceptions)
  • Catching the error and dumping raw chunk (simple fix)
• Reporter suggested: Buffering partial chunks until complete CALL_SITE_REGEXP match is found
• No fix merged: No PRs reference this issue, not mentioned in changelog

Recommendation

Status: KEEP OPEN

Reasoning: This is a confirmed, reproducible bug that affects wrangler's local development experience. The issue has recent maintainer engagement with discussion of potential solutions. The bug causes wrangler to crash completely when workers produce certain patterns of stderr output, which can happen randomly based on Node's internal chunking.

Action: Keep open for fix. The maintainer has acknowledged the issue and discussed approaches. A fix implementing one of the discussed solutions (catching the error or buffering chunks) would resolve this.