使用yeoman模板时未定义AngularJs提供程序

Question

来源：http://plnkr.co/edit/NpyTspWsY3rh0bzl9JUq

代码示例适用于plnkr。当我将代码复制到使用yeoman创建的新应用程序时，我收到以下错误：

ReferenceError: $hello is not defined
at $get (http://localhost:9000/scripts/app.js:21:16)
at Object.invoke (http://localhost:9000/components/angular/angular.js:2864:28)
at http://localhost:9000/components/angular/angular.js:2702:37
at getService (http://localhost:9000/components/angular/angular.js:2824:39)
at Object.invoke (http://localhost:9000/components/angular/angular.js:2842:13)
at http://localhost:9000/components/angular/angular.js:2702:37
at Object.getService [as get] (http://localhost:9000/components/angular/angular.js:2824:39)
at http://localhost:9000/components/angular/angular.js:9545:24
at filter (http://localhost:9000/components/angular/angular.js:6107:14)
at _filterChain (http://localhost:9000/components/angular/angular.js:6098:41) 

我无法找到为什么它适用于plnkr但不适用于新创建的角度应用程序。

yeoman应用程序看起来像这样：

'use strict';

angular.module('asdfApp', ['myHello'])
  .config(function ($routeProvider) {
    $routeProvider
      .when('/', {
        templateUrl: 'views/main.html',
        controller: 'MainCtrl'
      })
      .otherwise({
        redirectTo: '/'
      });
  });



var myModule = angular.module('myHello', []);

myModule.provider('$hello', function () {
    this.$get = function () {
        $hello = function (key) {
            return 'hello ' + key;
        };

        return $hello;
    }
});

myModule.filter('hello',function ($parse, $hello) {
    return function (key) {
        return $hello(key);
    };
});

当我将代码更改为此时，它在yeoman scaffolded app中工作（返回对象中的say函数）：

var myModule = angular.module('myHello', []);

myModule.provider('$hello', function () {
    this.$get = function () {
        var say = function (key) {
            return 'hello ' + key;
        };

        return { say : say};
    }
});

myModule.filter('hello',function ($parse, $hello) {
    return function (key) {
        return $hello.say(key);
    };
});