fix: add default export for mapAsyncIterator

[n1ru4l]

Previously the mapAsyncIterator function could be imported via

import mapAsyncIterator from 'graphql/subscription/mapAsyncIterator.js';

but the export was changed to import { mapAsyncIterator } from 'graphql/subscription/mapAsyncIterator.js';

Could we still have a default export for having easy backward compatibility without having to inline the function into our libraries?

[n1ru4l]

Using this instead (we already had that helper):

export async function* mapAsyncIterator<TInput, TOutput = TInput>(
  asyncIterable: AsyncGenerator<TInput, void, void> | AsyncIterable<TInput>,
  map: (input: TInput) => Promise<TOutput> | TOutput
): AsyncGenerator<TOutput, void, void> {
  for await (const value of asyncIterable) {
    yield map(value);
  }
}