fix cannot get register username/password

lib/call-session.js

@@ -273,7 +273,6 @@ class CallSession extends Emitter {
       }
 
       if (this.req.canceled) throw new Error('call canceled');
-      const {gateway} = this.req.locals;
 
       // now send the INVITE in towards the feature servers
       debug(`sending INVITE to ${proxy} with ${uri}`);
@@ -334,6 +333,7 @@ class CallSession extends Emitter {
       });
 
       // passing gateway outbound auth that sbc-inbound can send RE-INVITE with authentication process on UAS side
+      const {gateway} = this.req.locals;
       if (gateway.register_username && gateway.register_password) {
         this.logger.info('passing outbound gateway auth to CallSession for reinvite processing');
         uas.auth = {