angularDragula is not defined

Hi,

I purchaged “Triangular - Material Design Admin Template AngularJS”, it works fine as default. But after distribution (i.e. gulp build) it show an error “angularDragula is not defined” while run “gulp serve:dist”. I have spent lot of time to resolve this issue but unable to get solution. Please help me. This is default issue, nothing changes from my side.