title: Promise.all returning promise for array of promises, but returning correct value for single promise
body: <p>I am using Promise for Readfile from storage and convert to base64 string.
  I have array of images,using RNFS for read images</p>
  
  <pre><code>const promise_Images = _Images.map(async (nOPImg) =&gt; {
  
                      //get base 64 image
                      let image = await RNFS.readFile(nOPImg.photourl, 'base64')
                      nOPImg.photo = image
  
                     return nOPImg
                  }
  
          })
  
  const promise_Images2 = _Images.map(async (nOPImg) =&gt; {
  
                      //get base 64 image
                      let image = await RNFS.readFile(nOPImg.photourl, 'base64')
                      nOPImg.photo = image
  
                     return nOPImg
                  }
  
          })
  </code></pre>
  
  <p>Now if I use promise all just with single promise returning correct out put</p>
  
  <pre><code>Promise.all(promise_Images ).then(res =&gt; {
                  console.log("Image List", res)
  
                  })
  </code></pre>
  
  <p>But if I execute all the promises at once it returning promise</p>
  
  <pre><code> Promise.all(promise_Images1, promise_Images2  ).then(res =&gt; {
                  console.log("Image List", res)
  
                  })
  </code></pre>
  
  <p>result</p>
  
  <pre><code>0: Promise {_40: 1, _65: 1, _55: "/9j/4AAQSkZJRgABAQAAAQABAAD/2wBDABALDA4MChAODQ4SER…RQAUUUUAFFFFABQKKKACiiigAooooAKKKKACiiigAooooA//Z", _72: null}
  1: Promise {_40: 1, _65: 1, _55: "/9j/4AAQSkZJRgABAQAAAQABAAD/2wBDABALDA4MChAODQ4SER…FFABRRRQAUUUUAFFFFABRRRQAUUUUAFFFFABRRRQAUUUUAf/Z", _72: null}
  2: Promise {_40: 1, _65: 1, _55: undefined, _72: null}
  3: Promise {_40: 1, _65: 1, _55: undefined, _72: null}
  </code></pre>
  
  <p>How can I just return base64 string here ?</p>