Uncaught TypeError: Cannot read property 'cancel' of null

[nat-pierce]

Hi,

I am unsure if I am using this library correctly, I'm admittedly new to simple-peer altogether and recently discovered your library. I am trying to send multiple files from one browser to another (one at a time).

I managed to get multiple files to send with the following workflow:

1. When User A presses the send button, User A calls:
   peer.send('PREPARING_TO_SEND');
2. When User B receives the message, User B calls:

peer.on('data', data => {
            if (data === 'PREPARING_TO_SEND') {
                spf.receive(peer, `photo_${numPhotos}`).then(transfer => {
                    transfer.on('done', file => {
                        this.addPhoto(file);
                    });
                });

                peer.send('READY_FOR_FILE');
            }
        })

3. When User A receives the message, User A calls:

peer.on('data', data => {
            if (data === 'READY_FOR_FILE') {
                spf.send(peer, `photo_${numPhotos}`, this.fileToSend).then(transfer => {
                    transfer.on('done', () => {
                        numPhotos++;
                        this.fileToSend = null;
                    });
        
                    transfer.start()
                })
            }
        })

This all seems to work, but every photo sent I get the following console error:

Uncaught TypeError: Cannot read property 'cancel' of null
    at Peer.<anonymous> (index.js:60)

Where line 60 is here:

pfs.on('done', destroy);
                pfs.on('cancel', destroy);
                fileChannel.on('close', function () {
 ---->              pfs.cancel();
                });

What's going on here? Do I need to call spf.receive before each file like I'm doing? I tried just calling it once but I got the same error where the file channel would close.

There are no errors coming from my server (and neither user has left the room), and the receiver browser has no errors either

[nat-pierce]

I noticed that in your example you would do peer.send('READY_FOR_FILE'); in the promise of spf.receive(). When I do that, 'READY_FOR_FILE' never even gets sent

[davidchase]

@nat-pierce i ran into this issue as well, however reverting back to a previous version 1.2.2. seems to provide better results.

i must admit though recently i've been simply using https://github.com/subins2000/p2pt to send files over to peers, and for large files i simply chunk the file before sending and put it back together on the other side.

I found based on this feross/simple-peer#561 (comment) and article the ideal chunk size to be 16 KB. Ive played around with throttling as well when the files are larger.