Fixed attempt method not handling errors correctly

lib/backoff.js

@@ -4,12 +4,11 @@ var Promise = require('bluebird');
 var Errors = require('./errors');
 
 function Backoff(options) {
-  options = options || {};
   this.attempts = 0;
   this.minDelay = options.minDelay;
   this.maxDelay = options.maxDelay;
   this.useRandom = options.useRandom || false;
-  this.maxAttempts = options.maxAttempts || 5;
+  this.maxAttempts = options.maxAttempts;
 
   if(options.hasOwnProperty('maxDuration')) {
     this.maxDuration = options.maxDuration;
@@ -97,6 +96,7 @@ BackoffRunner.attempt = function(operation, options, done) {
     backoff.attempts++;
     operation(function() {
       if(arguments.length > 0 && arguments[0]) {
+        // The operation ended with an error.
         if(arguments[0] instanceof BackoffRunner.NonRetryableError) {
           // We shouldn't retry.
           return done(arguments[0]);
@@ -106,6 +106,9 @@ BackoffRunner.attempt = function(operation, options, done) {
           // Try again after the delay.
           return setTimeout(performOperation, delay);
         }
+
+        // Else, fail.
+        return done(arguments[0]);
       }
 
       // Otherwise, the operation succeeded!