Bug: lazy() permanently caches undefined when the initializer throws

Description

lazy() in packages/core/src/util/lazy.ts sets loaded = true before calling fn():

return (): T => {
  if (loaded) return value as T
  loaded = true
  value = fn()
  return value as T
}

If fn() throws, loaded is already true but value was never assigned. Every subsequent call then takes the if (loaded) fast path and silently returns undefined forever — the initializer never runs again, and the original error is swallowed.

That turns a transient failure into a permanent one, and replaces a clear error with a confusing undefined downstream.

Steps to reproduce

The synchronous lazy() callers that can throw are affected. Using the shape of packages/enterprise/src/core/storage.ts:86:

import { lazy } from "./src/util/lazy"

const adapter = lazy(() => {
  const type = process.env["OPENCODE_STORAGE_ADAPTER"]
  if (type === "s3") return { read: () => "s3" }
  throw new Error("No storage adapter configured")
})

try { adapter() } catch (e) { console.log("call 1:", e.message) }
process.env["OPENCODE_STORAGE_ADAPTER"] = "s3"
console.log("call 2:", adapter().read())

Actual:

call 1: No storage adapter configured
TypeError: undefined is not an object (evaluating 'adapter().read')

Expected: call 2 either succeeds, or at minimum repeats the real No storage adapter configured error instead of degrading into a TypeError about undefined.

Other synchronous callers with the same exposure: packages/opencode/src/server/server.ts:56, packages/opencode/src/server/routes/instance/httpapi/server.ts:188.

OS

Windows (behaviour is platform-independent — it is pure logic in the memoization guard)