prevent crash when a class claims to implement an interface but has no members

lib/jsdoc/augment.js

@@ -191,7 +191,7 @@ exports.addImplemented = function(docs) {
             // class's interfaces
             cls.implements.forEach(function(impl) {
                 var implProps = propertyInfo[impl];
-                var props = docMap[cls.longname];
+                var props = docMap[cls.longname] || [];
 
                 for (var i = 0, len = props.length; i < len; i++) {
                     var prop = props[i];

test/fixtures/interface-implements.js

@@ -63,3 +63,9 @@ IWorker.prototype.work = function() {};
 function MyWorker() {}
 MyWorker.prototype.work = function() {};
 MyWorker.prototype.process = function() {};
+
+/**
+ * @constructor
+ * @implements {IWorker}
+ */
+function MyIncompleteWorker() {}

test/specs/tags/implementstag.js

@@ -1,10 +1,11 @@
 /*global describe, expect, it, jasmine */
 'use strict';
 
-describe('@interface tag', function() {
+describe('@implements tag', function() {
     var docSet = jasmine.getDocSetFromFile('test/fixtures/interface-implements.js');
 
     var myTester = docSet.getByLongname('MyTester')[0];
+    var myIncompleteWorker = docSet.getByLongname('MyWorker')[0];
     var beforeEachMethod = docSet.getByLongname('MyTester#beforeEach')[0];
     var processMethod = docSet.getByLongname('MyWorker#process')[0];
 
@@ -22,4 +23,8 @@ describe('@interface tag', function() {
     it('MyWorker\'s process() method does not implement an interface', function() {
         expect(processMethod.implements).toBeUndefined();
     });
+
+    it('MyIncompleteWorker does not have any methods', function() {
+        expect(docSet.getByLongname('MyIncompleteWorker#work').length).toBe(0);
+    });
 });