Fix findByIdAndUpdate behavior with undefined id

lib/model.js

@@ -2621,6 +2621,10 @@ function _decorateUpdateWithVersionKey(update, options, versionKey) {
  *     A.findByIdAndUpdate()                     // returns Query
  *
  * ####Note:
+ * 
+ * If id is undefined and update is specified, an error will be thrown.
+ * 
+ * ####Note:
  *
  * All top level update keys which are not `atomic` operation names are treated as set operations:
  *
@@ -2676,6 +2680,9 @@ Model.findByIdAndUpdate = function(id, update, options, callback) {
       throw new TypeError(msg);
     }
     return this.findOneAndUpdate({ _id: id }, undefined);
+  } else if (arguments.length > 1 && id === undefined) {
+    const msg = 'Model.findByIdAndUpdate(): id cannot be undefined if update is specified.';
+    throw new TypeError(msg);
   }
 
   // if a model is passed in instead of an id

test/model.populate.test.js

@@ -316,6 +316,14 @@ describe('model: populate:', function() {
       });
   });
 
+  it('fail on undefined id update', function() {
+    const BlogPost = db.model('BlogPost', blogPostSchema);
+
+    assert.throws(function() {
+      BlogPost.findByIdAndUpdate(undefined, { $set: { _creator: {} } });
+    }, /id cannot be undefined/);
+  })
+
   it('across DBs', function(done) {
     const db = start();
     const db2 = db.useDb('mongoose_test2');