How to stop callback function for onHardwareBackButton? Ionic

Sorry if my english isn't perfect at all.

I am using $ionicPlatform.onHardwareBackButton to use with the Screen Orientation Plugin to change the orientation to portrait when you go back from a view when is playing a Youtube video, here is an example of what i am doing:

app.controller('nameCtrl', ['$ionicPlatform', function('$ionicPlatform') {

    $scope.openVideo = function(id) {
        var isVideoPlaying = true;

        // some stuff here

        if(isVideoPlaying) {
            $ionicPlatform.onHardwareBackButton(function() {
                screen.lockOrientation('portrait');
                isVideoPlaying = false;
                alert('going back');
            });
        } // in this line i get an error "TypeError: object is not a function" from GapDebug
    }

}]);

onHardwareBackButton detection works perfect, but when i am not playing a video the callback function is called too. Don't know why is not working with the boolean part. Any help? Sorry if is an stupid question.

I tried using semicolon in the line of the error based on GapDebug but nothing.

Thanks in advance

Try something like this:

app.controller('nameCtrl', ['$ionicPlatform', function('$ionicPlatform') {

    $scope.openVideo = function(id) {
        var isVideoPlaying = true;

        // some stuff here
        $ionicPlatform.onHardwareBackButton(function() {

            if(isVideoPlaying) {
                screen.lockOrientation('portrait');
                isVideoPlaying = false;
                alert('going back');
            } // in this line i get an error "TypeError: object is not a function" from GapDebug
        });

    }

}]);