Problem

When you start out with code like this:

myApp.controller('mainController', function($scope, $log) {
    console.log($scope);
});

Minifiers end up with something like this:

myApp.controller("mainController",function(o){console.log(o)});

Since the minified version renamed the $scope variable, you can no longer dependency inject $scope.

Inside the console, you see an error like this:

Solution

If you refactor the initial code to:

myApp.controller('mainController', ['$scope', '$log', function($scope, $log) {
    console.log($scope);
    console.log($log);
}]);

The minification turns out like:

myApp.controller("mainController",["$scope","$log",function(o,l){console.log(o),console.log(l)}]);

As you can imagine, o is substituted to $scope. The replacement is determined by order in the array.

Keep in mind that usually dependency injection in Angular is order agnostic, however when using this method, the order matters.

Solution #2

Alternatively:

    function mainController($scope, $log) {...}
    mainController.$inject = ['$scope', '$log'];
    myApp.controller('mainController', mainController);

Other notes:

AngularJS docs -> http://docs.angularjs.org/tutorial/step_05 . Scroll down to A Note on Minification.

Also alternatively, the ng-annotate library can be installed and run manually/automatically converting your original code to work with minification.

In the readme, there are automation tools support for grunt, gulp, rails, and a whole lot more.

For the gulp config files, its as simple as adding:

var ngAnnotate = require('gulp-ng-annotate'); //don't forget to npm install this!'
..//somewhere in a sample task definition

gulp.task('buildJSProduction', function () {
    return gulp.src(['./browser/js/app.js', './browser/js/**/*.js'])
        .pipe(concat('main.js'))
        .pipe(babel())              //ES6 compatability
        .pipe(ngAnnotate())         //allows for minification while preserving dependency injection variable names
        .pipe(uglify())             //we're using ngAnnotate to support minification :)
        .pipe(gulp.dest('./public'));
});