Added signaling error handling to webrtc-star transport (#39)

* Added a failing test that shows expected behaviour but is failing due to lack of error handling code.

* Added error handling to js-libp2p-webrtc-star so that unavailable peers do not cause error states.

Author: michaelfakhri

src/webrtc-star/index.js

@@ -75,6 +75,10 @@ function WebRTCStar () {
     })
 
     sioClient.on('ws-handshake', (offer) => {
+      if (offer.intentId === intentId && offer.err) {
+        return callback(new Error(offer.err))
+      }
+
       if (offer.intentId !== intentId || !offer.answer) {
         return
       }
@@ -135,7 +139,7 @@ function WebRTCStar () {
       })
 
       function incommingDial (offer) {
-        if (offer.answer) {
+        if (offer.answer || offer.err) {
           return
         }
 

test/webrtc-star/test-dial.js

@@ -59,6 +59,13 @@ describe('dial', () => {
       )
     })
   })
+  it('dial offline / non-existent node on IPv4, check callback', (done) => {
+    let maOffline = multiaddr('/libp2p-webrtc-star/ip4/127.0.0.1/tcp/15555/ws/ipfs/ABCD')
+    ws1.dial(maOffline, (err, conn) => {
+      expect(err).to.exist
+      done()
+    })
+  })
 
   it.skip('dial on IPv6', (done) => {
     // TODO IPv6 not supported yet