packages/mesh/lib/streams/std/writable-stream.js
function WritableStreamDefaultControllerError(controller, e) {
  const stream = controller._controlledWritableStream;

  assert(stream._state === 'writable' || stream._state === 'closing');

  WritableStreamError(stream, e);

  controller._queue = [];
}
function WritableStreamDefaultControllerError(controller, e) {
  const stream = controller._controlledWritableStream;

  assert(stream._state === 'writable' || stream._state === 'closing');

  WritableStreamError(stream, e);

  controller._queue = [];
}
A client of WritableStreamDefaultController may use these functions directly to bypass state check.