Using async / await inside async.auto chain leads to TypeError: callback is not a function

[gone-phishing]

What version of async are you using?
2.6.1

Which environment did the issue occur in (Node version/browser version)
8.11.3

What did you do? Please include a minimal reproducible case illustrating the issue.
Assuming fileObj is supplied from outside:

async.auto({
  download: (downloadCB) => {
    if (fileObj) {
      fs.writeFile(__dirname + ‘fileNew.txt’, fileObj.content, 'base64', function (err) {
        if (err){
          return downloadCB(err);
        }
        return downloadCB(null , fileObj.generatedFileName); // works fine
      });
    } else {
      let err = new Error('File not found');
      return downloadCB(err);
    }
  },
  collectData: ['download', async (results, collectCB) => {
    console.log(typeof collectCB); // prints undefined
    console.log(typeof results); // prints correct object
    
    let res = await anHttpRequest();
    if (res.response && res.response.statusCode == 200) {
      return collectCB(null , 'fileCombined.txt'); // This is where the ISSUE happens
    }
    else if(res.response.statusCode >= 300) {
      return collectCB(new Error('Request failed inside async-auto'));
    }
  }],

  filterData: ['collectData', (results, filterCB) => {
    doFilter(results.collectData, filterCB);
  }],
})

What did you expect to happen?
After collectData finishes execution, filterData should begin execution the param passed inside collectCB function

What was the actual result?
TypeError: collectCB is not a function.

The same code executes well with version 2.0.1 but after upgrade to 2.6.1 it has stopped working and its critical for us. Any work arounds will also be appreciated.

[aearly]

We treat async functions differently -- we do not pass them a callback. Instead, simply return a value (or throw an error).

[gone-phishing]

Yes, learnt about the same from StackOverflow and so posting a reference to same here, in case someone stumbles upon this in future: Using-async-await-inside-async-auto-chain

[woodbri]

This also applies to async.parallel if the functions are async you need to return the value not call the callback. This should get added to the documentation and examples.

        async.parallel({
            // NOTE: for async functions just return value or throw error
            // don't use the callback
            dates: async function(callback) {
                var rr = await getDates(dbName, r.indi, idx);
                return rr;
             },
             sdates: async function(callback) {
                  var rr = await getDates(dbName, r.spouse, idx);
                  return rr;
             },
             cdates: async function(callback) {
                  var rr = await getDates(dbName, r.cindi, idx);
                  return rr;
             }
        },
        function(err, results) {
             console.log(results);
        });

[aearly]

I'd like to re-write a lot of the examples in the docs to use more async/await, to highlight what you can do now.

[gone-phishing]

More than features in this package, we need docs. Will be great to see more examples in the future

[pankaj110987]

We treat async functions differently -- we do not pass them a callback. Instead, simply return a value (or throw an error).

@aearly can you please explain in details i am not getting. @gone-phishing

async.eachSeries([1,2,3], async(item, cb) => {
await delay(6000);
console.log(item);
//cb(null);
return item;
}, function(done,results) {
console.log(done);
console.log(results);
});

what mistake i am doing here i am not getting