node:diagnostics_channel: preserve non-callable bindStore transform errors #3085

Summary

Channel#bindStore(store, transform) should remember any non-undefined transform value. During runStores(), Node attempts to call that transform; if it is not callable, the callback still runs with no store context and Node reports an uncaught TypeError: transform is not a function. Perry currently discards any non-closure transform at bind time, so null, numbers, strings, and other non-callable transform values behave exactly like an omitted transform and no error is reported.

Node Behavior

Probe run with Node v25.9.0:

const { channel } = require("node:diagnostics_channel");
const { AsyncLocalStorage } = require("node:async_hooks");

process.on("uncaughtException", (err) => {
  console.log("uncaught:", err.name, err.code || "no-code", err.message);
  process.exitCode = 0;
});

for (const transform of [null, 1]) {
  const ch = channel("bind-transform-" + Math.random());
  const als = new AsyncLocalStorage();
  ch.bindStore(als, transform);
  const ret = ch.runStores({ value: 1 }, () => {
    console.log("callback store", als.getStore());
    return "ret";
  });
  console.log("returned", ret);
}

Observed behavior: the callback runs and returns, als.getStore() is undefined, and Node emits uncaught TypeError events with message transform is not a function for both null and numeric transform values. An omitted or explicit undefined transform does not report that error.

Perry Behavior

• crates/perry-runtime/src/node_submodules/diagnostics.rs::diag_channel_bind_store() computes let transform = if valid_closure_value(transform) { Some(transform) } else { None };.
• That means every non-callable transform is stored as None, indistinguishable from an omitted transform.
• diag_channel_run_stores() only attempts js_closure_call1(closure_ptr(t), data) when the stored transform is Some(t), so the Node TypeError path is skipped for non-callable transform values.
• Current store fixtures cover a valid transform and a throwing function transform, but not non-callable transform values.

Suggested PR Cut

Batch this with related issues in:
node:diagnostics_channel: tracing and store semantics parity cut (#3242)

Good batch candidates:

• node:diagnostics_channel: forward all runStores callback arguments #3082
• node:diagnostics_channel: implement Channel.withStoreScope disposable scopes #2632
• node:diagnostics_channel: honor traceCallback position and arguments #3086

Do not batch with:

• unrelated AsyncLocalStorage semantics outside diagnostics store binding
• worker/thread diagnostics subscriber policy changes
• tracing-channel category work in node:trace_events

Acceptance

• parity/regression test proves bindStore(store, null) followed by runStores() reports Node-compatible non-callable transform error behavior
• parity/regression test proves a numeric or string transform has the same error path
• omitted or explicit undefined transform remains the no-transform case
• wrapped callback execution and return value behavior remain Node-compatible
• related known-failure/docs/manifest entries updated if touched