Grunt serve works building doesn't work

[dev-myatminsoe]

(node:10565) ExperimentalWarning: The http2 module is an experimental API.
Running "resources:dist" (resources) task
>> build/js/resources.js

Running "concat:dist" (concat) task

Running "replace:dist" (replace) task
>> 61 replacements in 1 file.

Running "uglify:dist" (uglify) task
{ SyntaxError: Unexpected token: punc (()
    at JS_Parse_Error.get (<anonymous>:86:23)
    at formatError (util.js:610:16)
    at formatValue (util.js:514:18)
    at inspect (util.js:294:10)
    at format (util.js:161:12)
    at Console.log (console.js:130:21)
    at /Users/myatminsoe/Downloads/PixelDefense-master/src/node_modules/grunt-contrib-uglify/tasks/uglify.js:150:17
    at Array.forEach (<anonymous>:null:null)
    at Object.<anonymous> (/Users/myatminsoe/Downloads/PixelDefense-master/src/node_modules/grunt-contrib-uglify/tasks/uglify.js:76:16)
    at Object.<anonymous> (/Users/myatminsoe/Downloads/PixelDefense-master/src/node_modules/grunt/lib/grunt/task.js:252:15)
    at Object.thisTask.fn (/Users/myatminsoe/Downloads/PixelDefense-master/src/node_modules/grunt/lib/grunt/task.js:70:16)
    at Object.<anonymous> (/Users/myatminsoe/Downloads/PixelDefense-master/src/node_modules/grunt/lib/util/task.js:294:30)
    at Task.runTaskFn (/Users/myatminsoe/Downloads/PixelDefense-master/src/node_modules/grunt/lib/util/task.js:244:24)
    at Task.<anonymous> (/Users/myatminsoe/Downloads/PixelDefense-master/src/node_modules/grunt/lib/util/task.js:293:12)
    at /Users/myatminsoe/Downloads/PixelDefense-master/src/node_modules/grunt/lib/util/task.js:220:11
    at _combinedTickCallback (internal/process/next_tick.js:131:7)
    at process._tickCallback (internal/process/next_tick.js:180:9)

  message: 'Unexpected token: punc (()',
  filename: 'app.js',
  line: 31405,
  col: 11,
  pos: 1030139 }
>> Uglifying source build/js/app.js failed.
Warning: Uglification failed.
Unexpected token: punc ((). 
Line 31405 in build/js/app.js
 Use --force to continue.

Aborted due to warnings.