grunt fails when angular-ui-mask added

[kundusandeepan]

• karma fails
• reason the folder is not generated in build/vendor folder
• reason :grunt-contrib-copy fails to identify the file.

Gruntfile.js

...
function filterForJS ( files ) {
    grunt.log.writeln(files); // doesnt outputs the filename for UI mask.
    return files.filter( function ( file ) {
      return file.match( /\.js$/ );
    });
  }
...

bower.rc

{
  "directory": "vendor"
}

bower.json

{
  "name": "ng-boilerplate",
  "version": "0.3.2",
  "devDependencies": {
    "angular": "~1.5",
    "angular-mocks": "~1.5",
    "bootstrap": "~3.3",
    "angular-bootstrap": "~1.3",
    "angular-ui-router": "~0.2",
    "angular-ui-mask": "^1.8.3"
  },
  "dependencies": {}
}

Library name: angular-ui-mask

@joshdmiller your input requested.
Community: any information on this highly appreciated.