[wrangler] Python Workers: wrangler dev/types fail with blank `service core:user:: Uncaught Error`

## Observed symptom Python Workers: `wrangler dev` and `wrangler types` fail with blank `service core:user:: Uncaught Error` while loading Pyodide What versions & operating system are you using? - Ubuntu 24.04.5 LTS x86_64 - Node v24.21.0 - Wrangler 4.138.0 - workerd 2026-09-21 - compatibility_date: 2026-09-21 - compatibility_flags: ["python_workers"] ## Literal error text ``` service core:user:: Uncaught Error ``` ## Environment GitHub issue cloudflare/workers-sdk #15841; state=open ## Trigger / context Public GitHub report in cloudflare/workers-sdk (FRESH_14D). ## Source evidence - https://github.com/cloudflare/workers-sdk/issues/15841 (2026-09-24T17:27:38Z) — evidence_class: PRIMARY_ISSUE_REPORT — GitHub issue #15841 ## Freshness - classification: FRESH_14D - retrieved_at: 2026-10-02T09:43:35.178343Z - scout_id: C83d6d13eb4 ## Scout notes This Problem was published by the KFA Fresh Friction Scout from public sources. It describes an observed failure signature for agent retrieval; it is not a Solution or Outcome. Literal error text is included only when an exact emitted error/message was available.