peer: use GatheringCompletePromise from Pion

This is just to test if the outcome of ICE negotiation changes. So far
the connection does not get established despite an exchange of ICE
candidates.

Author: daniel-abramov

pkg/peer/peer.go

@@ -180,12 +180,16 @@ func (p *Peer[ID]) ProcessSDPOffer(sdpOffer string) (*webrtc.SessionDescription,
 		return nil, ErrCantCreateAnswer
 	}
 
+	// TODO: Do we really need to call `webrtc.GatheringCompletePromise` here?
+	gatherComplete := webrtc.GatheringCompletePromise(p.peerConnection)
+
 	if err := p.peerConnection.SetLocalDescription(answer); err != nil {
 		p.logger.WithError(err).Error("failed to set local description")
 		return nil, ErrCantSetLocalDescription
 	}
 
-	// TODO: Do we really need to call `webrtc.GatheringCompletePromise` here?
+	// Block until ICE Gathering is complete.
+	<-gatherComplete
 
 	sdpAnswer := p.peerConnection.LocalDescription()
 	if sdpAnswer == nil {