"window.angular is undefined." when using protractor for automated testing?

I seem to have an error when using the example conf.js provided with protractor. I am running my tests with grunt-protractor-runner but it errors even when using the example config provided.

My Gruntfile.js looks like this:

/*global module:false*/
module.exports = function(grunt) {
  // Project configuration.
    grunt.initConfig({
      protractor: {
        options: {
          configFile: "smoketest.conf.js", // Default config file
          keepAlive: false, // If false, the grunt process stops when the test fails.
          noColor: false, // If true, protractor will not use colors in its output.
          webdriverManagerUpdate: true,
          args: {
            seleniumServerJar: './node_modules/protractor/selenium/selenium-server-standalone-2.51.0.jar'
          }
        },
        smoke_test: {   // Grunt requires at least one target to run so you can simply put 'all: {}' here too.
          options: {
            configFile: "smoketest.conf.js", // Target-specific config file
            args: {
              }
          }
        },
        protractor_test: {   // Grunt requires at least one target to run so you can simply put 'all: {}' here too.
            options: {
                configFile: "./node_modules/protractor/example/conf.js", // Target-specific config file
                args: {
                }
            }
        },


      },
    })

  grunt.loadNpmTasks('grunt-protractor-runner');
  // Default task.
  grunt.registerTask('default', ['protractor:smoke_test']);

};

I am running grunt protractor:protractor_test which uses this file:

describe('angularjs homepage', function() {
  it('should greet the named user', function() {
    browser.get('http://www.angularjs.org');

    element(by.model('yourName')).sendKeys('Julie');

    var greeting = element(by.binding('yourName'));

    expect(greeting.getText()).toEqual('Hello Julie!');
  });

  describe('todo list', function() {
    var todoList;

    beforeEach(function() {
      browser.get('http://www.angularjs.org');

      todoList = element.all(by.repeater('todo in todoList.todos'));
    });

    it('should list todos', function() {
      expect(todoList.count()).toEqual(2);
      expect(todoList.get(1).getText()).toEqual('build an angular app');
    });

    it('should add a todo', function() {
      var addTodo = element(by.model('todoList.todoText'));
      var addButton = element(by.css('[value="add"]'));

      addTodo.sendKeys('write a protractor test');
      addButton.click();

      expect(todoList.count()).toEqual(3);
      expect(todoList.get(2).getText()).toEqual('write a protractor test');
    });
  });
});

however, when this runs i am presented with the error

Error while waiting for Protractor to sync with the page: "window.angular is undefined.  This could be either because this is a non-angular page or because your test involves client-side navigation, which can interfere with Protractor's bootstrapping.  See http://git.io/v4gXM for details"`enter code here`

I have been to http://git.io/v4gXM but i cannot seem to find anything to fix my issue? Has anybody else had this issue, surely the example test should work always??