fixed; RangeError in ValidationError.toString()

closes #1296

lib/errors/validation.js

@@ -25,9 +25,15 @@ function ValidationError (instance) {
  */
 
 ValidationError.prototype.toString = function () {
-  return this.name + ': ' + Object.keys(this.errors).map(function (key) {
-    return String(this.errors[key]);
-  }, this).join(', ');
+  var ret = this.name + ': ';
+  var msgs = [];
+
+  Object.keys(this.errors).forEach(function (key) {
+    if (this == this.errors[key]) return;
+    msgs.push(String(this.errors[key]));
+  }, this)
+
+  return ret + msgs.join(', ');
 };
 
 /*!

test/errors.validation.test.js

@@ -0,0 +1,39 @@
+
+/**
+ * Module dependencies.
+ */
+
+var assert = require('assert')
+  , start = require('./common')
+  , mongoose = start.mongoose
+  , EmbeddedDocument = require('../lib/types/embedded')
+  , DocumentArray = require('../lib/types/documentarray')
+  , Schema = mongoose.Schema
+  , SchemaType = mongoose.SchemaType
+  , ValidatorError = SchemaType.ValidatorError
+  , ValidationError = mongoose.Document.ValidationError
+
+describe('ValidationError', function(){
+  describe('#toString', function(){
+    it('does not cause RangeError (gh-1296)', function(done){
+      var ASchema = new Schema({
+          key: {type: String, required: true}
+        , value: {type:String, required: true}
+      })
+
+      var BSchema = new Schema({
+          contents: [ASchema]
+      })
+
+      var M = mongoose.model('A', BSchema);
+      var m = new M;
+      m.contents.push({ key: 'asdf' });
+      m.validate(function (err) {
+        assert.doesNotThrow(function(){
+          String(err)
+        })
+        done();
+      });
+    })
+  })
+})