events.once(process.stdout, name) with a name typed "drain" returned the
pending promise without evaluating the name, so a call or comma
expression producing "drain" never ran. A name that is not a string
literal now runs before the promise is created.
A write completion callback that returns a value (`() => count++`, a
stored function typed `(): number`) reported SC2020. The stream ignores
the return value, so such a callback is adapted to return nothing, as
before the error-argument form was added.
The stream-shims npm case compiles and matches Node now that write
callbacks take the error argument, so its SC2020 expectation is removed.
`writable.write(chunk, cb)` with `cb` passed as a function VALUE lost the
completion's error: `lowerWriteCb` checked only the callback's syntax and
lowered every other callback through `lowerExprExpecting(cbArg,
funcOf([], VOID))`, which adapts a one-parameter function down to zero
parameters. The native binary therefore printed `undefined` where Node
prints `null`, or the write's own error (`ERR_STREAM_WRITE_AFTER_END` /
`ERR_STREAM_DESTROYED` for late and destroyed writes).
Lower such callbacks through a new `writable.writeEcb` libCall
`(recv, mode, chunk, encoding, cb)`: a zero-parameter callback keeps the
existing synchronous path, and a callback that declares the error (a dyn
value, or `null | Error`) is wrapped by `scr_stream_ecb_wrap` with the
compiler-built adapter that delivers the error the write completion
carries. The stream unit publishes that error only in its
`SCR_STREAM_WRITE_ERRORS` build, selected by the new `streamWriteErrors`
runtime feature (rule: any `writable.writeEcb`). Every other build
compiles `SCR_WCB_CALL` to the same plain call, so their objects are
unchanged.
The destruction path also matched Node: `afterWrite` calls `cb(null)`
even for a stream destroyed after the write was queued (Node 24
`internal/streams/writable`), so the destroyed `SCR_ST_AFTER_WRITE` tick
passes NULL rather than the stream's stored error.
Corpus: `tests/corpus/writable-error-callbacks.ts` covers success, an
erroring write, a write after end, and a write on a destroyed stream.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Chris Tate