fix: prevent undefined error during a mutual hangup

Author: jacobheun

src/dial.js

@@ -267,8 +267,9 @@ class Dialer {
           }
 
           const muxedConn = this.switch.muxers[key].dialer(conn)
-          this.switch.muxedConns[b58Id] = {}
-          this.switch.muxedConns[b58Id].muxer = muxedConn
+          this.switch.muxedConns[b58Id] = {
+            muxer: muxedConn
+          }
 
           muxedConn.once('close', () => {
             delete this.switch.muxedConns[b58Id]

src/index.js

@@ -110,6 +110,11 @@ class Switch extends EE {
     this.stats.stop()
     series([
       (cb) => each(this.muxedConns, (conn, cb) => {
+        // If the connection was destroyed while we are hanging up, continue
+        if (!conn) {
+          return cb()
+        }
+
         conn.muxer.end((err) => {
           // If OK things are fine, and someone just shut down
           if (err && err.message !== 'Fatal error: OK') {