Closure in a let/const initializer cannot see the binding that declarator introduces (ReferenceError; breaks claude install) #9718

A closure created inside a let/const declarator's initializer that references the binding that declarator introduces is compiled as if the binding did not exist: calling it later throws ReferenceError: <name> is not defined. Node only has a TDZ window here, so a callback invoked after initialization is required to work.

Minimized, fails on current main (0e3ce3812):

const mk = (o: { cb: () => void }): Promise<{ u: () => void }> => {
  setTimeout(o.cb, 1);
  return Promise.resolve({ u: () => console.log("unmount") });
};

async function call(): Promise<void> {
  const { u: O } = await mk({ cb: () => { O(); } });   // <- O declared by THIS declarator
  console.log("call returned");
}
void call();

node  : call returned / unmount
perry : call returned / ReferenceError: O is not defined

Which shapes fail

A closure created after the declaration sees the binding fine. Every shape where the closure is built in the initializer fails, so this is not destructuring-specific:

Repro files as used: test-files/ fixture in the PR; the matrix above is a single program that prints one line per shape.

Where it bites in the wild

This is the root cause of the B60_install_badtarget divergence carried in #9575 (claude install not-a-version: node exits 1, perry exits 0 with one byte less stdout). cli_2.1.112.js's install subcommand is exactly this shape:

let { unmount: O } = await eB(el(wMA, { onDone: (w, $) => { O(), q(w, $) }, force: z, target: A }))

onDone fires after the render resolves, throws ReferenceError: O is not defined, and claude-code logs uncaught_exception (3/3 runs, CLAUDE_CODE_DIAGNOSTICS_FILE). The uncaught throw is what drops the trailing newline and the exit code — so B60 is not an install-path bug at all, and #9487's closure did not miss a hunk.

Two observable consequences worth noting separately:

1. ReferenceError: <name> is not defined where the binding demonstrably exists in the enclosing scope — capture analysis is not putting the declarator's own binding in scope for closures inside its initializer.
2. The uncaught exception exits 0 under perry (node exits 1 on an uncaught exception). That second part may deserve its own fix.

Suspect area: closure capture collection (collect_local_refs_expr and friends) walks the declarator initializer before the declarator's binding is registered in the enclosing scope, so the free variable resolves to nothing instead of to the (still-uninitialized) local.