Check for pc.readyState && !== 'closed'

lib/negotiator.js

@@ -208,7 +208,7 @@ Negotiator.cleanup = function(connection) {
 
   var pc = connection.pc;
 
-  if (!!pc && (pc.readyState !== 'closed' || pc.signalingState !== 'closed')) {
+  if (!!pc && ((pc.readyState && pc.readyState !== 'closed') || pc.signalingState !== 'closed')) {
     pc.close();
     connection.pc = null;
   }