Unhandled rejection TypeError: expecting a function but got [object Object]

Can some one help me with this error please? So i'm using promise to go through my directory list files then open them but i'm getting this error:

Unhandled rejection TypeError: expecting an array or an iterable object but got [object Null] at apiRejection (/Users/aityahiamarwane/Desktop/availabilityNodejs/node_modules/bluebird/js/release/promise.js:10:27) at MappingPromiseArray.init (/Users/aityahiamarwane/Desktop/availabilityNodejs/node_modules/bluebird/js/release/promise_array.js:63:19) at MappingPromiseArray._asyncInit (/Users/aityahiamarwane/Desktop/availabilityNodejs/node_modules/bluebird/js/release/map.js:30:10) at Async._drainQueue (/Users/aityahiamarwane/Desktop/availabilityNodejs/node_modules/bluebird/js/release/async.js:138:12) at Async._drainQueues (/Users/aityahiamarwane/Desktop/availabilityNodejs/node_modules/bluebird/js/release/async.js:143:10) at Immediate.Async.drainQueues [as _onImmediate] (/Users/aityahiamarwane/Desktop/availabilityNodejs/node_modules/bluebird/js/release/async.js:17:14) at processImmediate [as _immediateCallback] (timers.js:383:17)

here's my code :

const Promise = require('bluebird');
fs = Promise.promisifyAll(require('fs'));

// Promise.map([functions],{concurrency:3})
// .then(res)
// .catch(err=>console.log(err));

function getFileNames(){
    return fs.readdirAsync('./availibility/')
    .then(res=>{        
        finalfilenames = Object.keys(res).map(objkey=>{
            if(res[objkey].startsWith('revision'))
                return res[objkey];
        }).filter(item=>item && item!=null).map(item=> fs.readFileAsync('./availibility/'+item, "utf8"))
    });     
        return finalfilenames;

};

getFileNames()
.then(mypromises=>
    {
        //mypromises = mypromises.slice(0,5);
        console.log(mypromises);
        Promise.map(mypromises,{concurrency:3})})
.then(finalresults => console.log(finalresults));

Is it a problem with the way I map ?

thank you,

via Marou Aityahia