webpack + angular 1.X doesn't work - angularjs

Question

I am trying to use webpack in my existing angularjs [1.4.7] application. I have one custom module which is getting generated as a bundle using webpack. I am later adding that custom module as a dependency in some other module. I don't get any error while generating bundle. But when I use this module as a dependency , it's throwing below error. I have tried everything possible and can't understand what's wrong here.
Error
Failed to instantiate module Module2 due to:
Error: [$injector:modulerr]..........
This error occurs when a module fails to load due to some exception. The error message above should provide additional context.
A common reason why the module fails to load is that you've forgotten to include the file with the defined module or that the file couldn't be loaded.
Code Snippet
webpack.config.js
module.exports = {
entry: {
app: [ './src/main/resources/js/app/app.module.js' ]
},
output: {
filename: './src/main/resources/js/app/bundle.js'
},
node: {
module: "empty",
net:"empty",
fs: "empty"
},
watch: false
};
app.module.js
'use strict';
var angular = require('angular');
module.exports = angular.module('module1', [
require('./components/services').name,
require('./components/controllers').name,
require('./components/directives').name
]);
components/services/index.js
'use strict';
var angular = require('angular');
module.exports = angular.module('services',[])
.factory('Service1', require('./Service1'))
.factory( 'Service2' , require('.Service2'))
components/services/service1.js
module.exports = function Service1( $q)
{
var service1 = {};
// service implementation
return service1;
};
components/controllers/index.js
'use strict';
var angular = require('angular');
module.exports = angular.module('controllers',[])
.controller('controller1' , require('./controller1'))
.controller('controller2' , require('./controller2'));
components/directives/index.js
'use strict';
var angular = require('angular');
module.exports = angular.module('directives',['services'])
.directive('directive1', require('./directive1'))
.directive('directive2' , require('./directive2'))
index.html
<script src="bundle.js" type="text/javascript"></script>
another app.js
var app2 = angular.module('Module2',['ui.router','ui.bootstrap','module1']);

Answer 1

Try adding your second module in the entry:
entry: {
app: [
'./src/main/resources/js/app/app.module.js',
'./src/main/resources/js/app/app.js'
]
},
It will help defining your module at first. Also I didn't see any reference to module2 in your code.