fix: node 16 passthrough multiple callback error

[ngraef]

Node 16 includes a behavior change that breaks many stream implementation functions if they use async/await syntax. Async functions implicitly return a Promise, and node's stream internals automatically call the underlying callback if the function's result is a thenable. There is some logic to skip the automatic callback if it was already called explicitly in the function; however, this can execute before other asynchronous tasks, which results in a ERR_MULTIPLE_CALLBACK error when the explicit callback is invoked. For example, the callback in this drain event handler will often trigger the error:

async transform(chunk, encoding, cb) {
  if (!forkStream.write(chunk)) {
    forkStream.once('drain', () => {
      cb(null, chunk);
    });
  } else {
    cb(null, chunk);
  }
}

This new behavior for thenables is undocumented and has already been deprecated. Unfortunately, we need to live with it for now. The most straightforward solution is to use a Promise chain instead of async/await in NodeClam passthrough()'s Transform implementation.

This PR also makes a change to use stream.Readable in jsdoc instead of ReadableStream from the experimental Web Streams API. (Complementary types change in DefinitelyTyped/DefinitelyTyped#58698.)

Fixes #82

Refs nodejs/node#39535, nodejs/node#40773

[kylefarris]

Thanks for the PR! I'm reviewing and testing it now.

[kylefarris]

Hey man, very thorough explanation. You had to dive deep into this issue to understand it and I really appreciate the help! All the tests have passed--everything looks good. I'm going to merge this as soon as I add you as a contributor.

[kylefarris]

New version: 2.0.2 has been pushed to NPM.

[ngraef]

Thanks for the quick review and release!