fix(document): don't emit model error if callback specified for consi…

…stency with docs

Fix #5216

lib/model.js

@@ -34,7 +34,7 @@ var VERSION_WHERE = 1,
  *
  * @param {Object} doc values with which to create the document
  * @inherits Document http://mongoosejs.com/docs/api.html#document-js
- * @event `error`: If listening to this event, it is emitted when a document was saved without passing a callback and an `error` occurred. If not listening, the event bubbles to the connection used to create this Model.
+ * @event `error`: If listening to this event, 'error' is emitted when a document was saved without passing a callback and an `error` occurred. If not listening, the event bubbles to the connection used to create this Model.
  * @event `index`: Emitted after `Model#ensureIndexes` completes. If an error occurred it is passed with the event.
  * @event `index-single-start`: Emitted when an individual index starts within `Model#ensureIndexes`. The fields and options being used to build the index are also passed with the event.
  * @event `index-single-done`: Emitted when an individual index finishes within `Model#ensureIndexes`. If an error occurred it is passed with the event. The fields, options, and index name are also passed.

lib/services/model/applyHooks.js

@@ -123,7 +123,9 @@ function applyHooks(model, schema) {
               if (error instanceof VersionError) {
                 error.stack = originalError.stack;
               }
-              _this.$__handleReject(error);
+              if (!fn) {
+                _this.$__handleReject(error);
+              }
               reject(error);
               return;
             }
@@ -140,8 +142,8 @@ function applyHooks(model, schema) {
           if (this.constructor.$wrapCallback) {
             fn = this.constructor.$wrapCallback(fn);
           }
-          return promise.then(
-            function() {
+          promise.then(
+            function(res) {
               process.nextTick(function() {
                 fn.apply(null, [null].concat($results));
               });