Fix error handling for malformed plain response

Author: grs

lib/sasl.js

@@ -57,7 +57,7 @@ var PlainServer = function(callback) {
 PlainServer.prototype.start = function(response, hostname) {
     var fields = extract(response);
     if (fields.length !== 3) {
-        this.connection.sasl_failed('Unexpected response in PLAIN, got ' + fields.length + ' fields, expected 3');
+        return Promise.reject('Unexpected response in PLAIN, got ' + fields.length + ' fields, expected 3');
     }
     var self = this;
     return Promise.resolve(this.callback(fields[1], fields[2], hostname))
@@ -208,7 +208,11 @@ SaslServer.prototype.do_fail = function (e) {
     var frame = frames.sasl_frame(frames.sasl_outcome({code: sasl_codes.SYS}));
     this.transport.encode(frame);
     this.connection.output();
-    this.connection.sasl_failed('Sasl callback promise failed' + e, 'amqp:internal-error');
+    try {
+        this.connection.sasl_failed('Sasl callback promise failed with ' + e, 'amqp:internal-error');
+    } catch (e) {
+        console.error('Uncaught error: ', e.message);
+    }
 };
 
 SaslServer.prototype.has_writes_pending = function () {