angularjs - Yoeman task "autoprefixer:dist" gets stuck -

i'm pretty new grunt workflow. have installed https://github.com/daftmonk/generator-angular-fullstack. when run grunt serve, gets stuck @ autoprefixer:dist task. when commented out autoprefixer task rest of task go through , app running. not sure whats wrong. please me rid of bottle neck, i'm pretty sure 1 line answer question. here's gruntfile

'use strict';    module.exports = function(grunt) {      // load grunt tasks automatically, when needed    require('jit-grunt')(grunt, {      express: 'grunt-express-server',      useminprepare: 'grunt-usemin',      ngtemplates: 'grunt-angular-templates',      cdnify: 'grunt-google-cdn',      protractor: 'grunt-protractor-runner',      injector: 'grunt-asset-injector'    });      // time how long tasks take. can when optimizing build times    require('time-grunt')(grunt);      // define configuration tasks    grunt.initconfig({      connect: {        server: {          options: {            port: 9000,            hostname: 'localhost'          },          proxies: [{            context: '/v1/',            host: 'localhost',            port: 8003,            https: false,            changeorigin: false,            xforward: false          }]        },        livereload: {          options: {            middleware: function(connect, options) {              if (!array.isarray(options.base)) {                options.base = [options.base];              }                // setup proxy              var middlewares = [require('grunt-connect-proxy/lib/utils').proxyrequest];                // serve static files.              options.base.foreach(function(base) {                middlewares.push(connect.static(base));              });                // make directory browse-able.              var directory = options.directory || options.base[options.base.length - 1];              middlewares.push(connect.directory(directory));                return middlewares;            }          }        }        },        // project settings      yeoman: {        // configurable paths        client: require('./bower.json').apppath || 'client',        dist: 'dist'      },      express: {        options: {          port: process.env.port || 9000        },          dev: {          options: {            script: 'server/app.js',            debug: true          }          },        prod: {          options: {            script: 'dist/server/app.js'          }        }      },      open: {        server: {          url: 'http://localhost:<%= express.options.port %>'        }      },      watch: {        injectjs: {          files: [            '<%= yeoman.client %>/{app,components}/**/*.js',            '!<%= yeoman.client %>/{app,components}/**/*.spec.js',            '!<%= yeoman.client %>/{app,components}/**/*.mock.js',            '!<%= yeoman.client %>/app/app.js'          ],          tasks: ['injector:scripts']        },        injectcss: {          files: [            '<%= yeoman.client %>/{app,components}/**/*.css'          ],          tasks: ['injector:css']        },        mochatest: {          files: ['server/**/*.spec.js'],          tasks: ['env:test', 'mochatest']        },        jstest: {          files: [            '<%= yeoman.client %>/{app,components}/**/*.spec.js',            '<%= yeoman.client %>/{app,components}/**/*.mock.js'          ],          tasks: ['newer:jshint:all', 'karma']        },        gruntfile: {          files: ['gruntfile.js']        },        livereload: {          files: [            '{.tmp,<%= yeoman.client %>}/{app,components}/**/*.css',            '{.tmp,<%= yeoman.client %>}/{app,components}/**/*.html',            '{.tmp,<%= yeoman.client %>}/{app,components}/**/*.js',            '!{.tmp,<%= yeoman.client %>}{app,components}/**/*.spec.js',            '!{.tmp,<%= yeoman.client %>}/{app,components}/**/*.mock.js',            '<%= yeoman.client %>/assets/images/{,*//*}*.{png,jpg,jpeg,gif,webp,svg}'          ],          options: {            livereload: true          }        },        express: {          files: [            'server/**/*.{js,json}'          ],          tasks: ['express:dev', 'wait'],          options: {            livereload: true,            nospawn: true //without option specified express won't reloaded          }        }      },        // make sure code styles par , there no obvious mistakes      jshint: {        options: {          jshintrc: '<%= yeoman.client %>/.jshintrc',          reporter: require('jshint-stylish')        },        server: {          options: {            jshintrc: 'server/.jshintrc'          },          src: ['server/{,*/}*.js']        },        all: [          '<%= yeoman.client %>/{app,components}/**/*.js',          '!<%= yeoman.client %>/{app,components}/**/*.spec.js',          '!<%= yeoman.client %>/{app,components}/**/*.mock.js'        ],        test: {          src: [            '<%= yeoman.client %>/{app,components}/**/*.spec.js',            '<%= yeoman.client %>/{app,components}/**/*.mock.js'          ]        }      },        // empties folders start fresh      clean: {        dist: {          files: [{            dot: true,            src: [              '.tmp',              '<%= yeoman.dist %>/*',              '!<%= yeoman.dist %>/.git*',              '!<%= yeoman.dist %>/.openshift',              '!<%= yeoman.dist %>/procfile'            ]          }]        },        server: '.tmp'      },        // add vendor prefixed styles      autoprefixer: {        options: {          browsers: ['last 1 version']        },        dist: {          files: [{            expand: true,            cwd: '.tmp/',            src: '{,*/}*.css',            dest: '.tmp/'          }]        }      },        // debugging node inspector      'node-inspector': {        custom: {          options: {            'web-host': 'localhost'          }        }      },        // use nodemon run server in debug mode initial breakpoint      nodemon: {        debug: {          script: 'server/app.js',          options: {            nodeargs: ['--debug-brk'],            env: {              port: process.env.port || 9000            },            callback: function(nodemon) {              nodemon.on('log', function(event) {                console.log(event.colour);              });                // opens browser on initial server start              nodemon.on('config:update', function() {                settimeout(function() {                  require('open')('http://localhost:8080/debug?port=5858');                }, 500);              });            }          }        }      },        // automatically inject bower components app      bowerinstall: {        target: {          src: '<%= yeoman.client %>/index.html',          ignorepath: '<%= yeoman.client %>/',          exclude: [/bootstrap-sass-official/]        }      },        // renames files browser caching purposes      rev: {        dist: {          files: {            src: [              '<%= yeoman.dist %>/public/{,*/}*.js',              '<%= yeoman.dist %>/public/{,*/}*.css',              '<%= yeoman.dist %>/public/assets/images/{,*/}*.{png,jpg,jpeg,gif,webp,svg}',              '<%= yeoman.dist %>/public/assets/fonts/*'            ]          }        }      },        // reads html usemin blocks enable smart builds automatically      // concat, minify , revision files. creates configurations in memory      // additional tasks can operate on them      useminprepare: {        html: ['<%= yeoman.client %>/index.html'],        options: {          dest: '<%= yeoman.dist %>/public'        }      },        // performs rewrites based on rev , useminprepare configuration      usemin: {        html: ['<%= yeoman.dist %>/public/{,*/}*.html'],        css: ['<%= yeoman.dist %>/public/{,*/}*.css'],        js: ['<%= yeoman.dist %>/public/{,*/}*.js'],        options: {          assetsdirs: [            '<%= yeoman.dist %>/public',            '<%= yeoman.dist %>/public/assets/images'          ],          // update image references in our ng-templates          patterns: {            js: [              [/(assets\/images\/.*?\.(?:gif|jpeg|jpg|png|webp|svg))/gm, 'update js reference our revved images']            ]          }        }      },        // following *-min tasks produce minified files in dist folder      imagemin: {        dist: {          files: [{            expand: true,            cwd: '<%= yeoman.client %>/assets/images',            src: '{,*/}*.{png,jpg,jpeg,gif}',            dest: '<%= yeoman.dist %>/public/assets/images'          }]        }      },        svgmin: {        dist: {          files: [{            expand: true,            cwd: '<%= yeoman.client %>/assets/images',            src: '{,*/}*.svg',            dest: '<%= yeoman.dist %>/public/assets/images'          }]        }      },        // allow use of non-minsafe angularjs files. automatically makes      // minsafe compatible uglify not destroy ng references      ngmin: {        dist: {          files: [{            expand: true,            cwd: '.tmp/concat',            src: '*/**.js',            dest: '.tmp/concat'          }]        }      },        // package html partials single javascript payload      ngtemplates: {        options: {          // should name of apps angular module          module: 'fullstackapp',          htmlmin: {            collapsebooleanattributes: true,            collapsewhitespace: true,            removeattributequotes: true,            removeemptyattributes: true,            removeredundantattributes: true,            removescripttypeattributes: true,            removestylelinktypeattributes: true          },          usemin: 'app/app.js'        },        main: {          cwd: '<%= yeoman.client %>',          src: ['{app,components}/**/*.html'],          dest: '.tmp/templates.js'        },        tmp: {          cwd: '.tmp',          src: ['{app,components}/**/*.html'],          dest: '.tmp/tmp-templates.js'        }      },        // replace google cdn references      cdnify: {        dist: {          html: ['<%= yeoman.dist %>/*.html']        }      },        // copies remaining files places other tasks can use      copy: {        dist: {          files: [{            expand: true,            dot: true,            cwd: '<%= yeoman.client %>',            dest: '<%= yeoman.dist %>/public',            src: [              '*.{ico,png,txt}',              '.htaccess',              'bower_components/**/*',              'assets/images/{,*/}*.{webp}',              'assets/fonts/**/*',              'index.html'            ]          }, {            expand: true,            cwd: '.tmp/images',            dest: '<%= yeoman.dist %>/public/assets/images',            src: ['generated/*']          }, {            expand: true,            dest: '<%= yeoman.dist %>',            src: [              'package.json',              'server/**/*'            ]          }]        },        styles: {          expand: true,          cwd: '<%= yeoman.client %>',          dest: '.tmp/',          src: ['{app,components}/**/*.css']        }      },        // run tasks in parallel speed build process      concurrent: {        server: [],        test: [],        debug: {          tasks: [            'nodemon',            'node-inspector'          ],          options: {            logconcurrentoutput: true          }        },        dist: [          'imagemin',          'svgmin'        ]      },        // test settings      karma: {        unit: {          configfile: 'karma.conf.js',          singlerun: true        }      },        mochatest: {        options: {          reporter: 'spec'        },        src: ['server/**/*.spec.js']      },        protractor: {        options: {          configfile: 'protractor.conf.js'        },        chrome: {          options: {            args: {              browser: 'chrome'            }          }        }      },        env: {        test: {          node_env: 'test'        },        prod: {          node_env: 'production'        },        all: require('./server/config/local.env')      },        injector: {        options: {          },        // inject application script files index.html (doesn't include bower)        scripts: {          options: {            transform: function(filepath) {              filepath = filepath.replace('/client/', '');              filepath = filepath.replace('/.tmp/', '');              return '<script src="' + filepath + '"></script>';            },            starttag: '<!-- injector:js -->',            endtag: '<!-- endinjector -->'          },          files: {            '<%= yeoman.client %>/index.html': [              ['{.tmp,<%= yeoman.client %>}/{app,components}/**/*.js',                '!{.tmp,<%= yeoman.client %>}/app/app.js',                '!{.tmp,<%= yeoman.client %>}/{app,components}/**/*.spec.js',                '!{.tmp,<%= yeoman.client %>}/{app,components}/**/*.mock.js'              ]            ]          }        },          // inject component css index.html        css: {          options: {            transform: function(filepath) {              filepath = filepath.replace('/client/', '');              filepath = filepath.replace('/.tmp/', '');              return '<link rel="stylesheet" href="' + filepath + '">';            },            starttag: '<!-- injector:css -->',            endtag: '<!-- endinjector -->'          },          files: {            '<%= yeoman.client %>/index.html': [              '<%= yeoman.client %>/{app,components}/**/*.css'            ]          }        }      },    });        grunt.loadnpmtasks('grunt-connect-proxy');    grunt.loadnpmtasks('grunt-autoprefixer');      // used delaying livereload until after server has restarted    grunt.registertask('wait', function() {      grunt.log.ok('waiting server reload...');        var done = this.async();        settimeout(function() {        grunt.log.writeln('done waiting!');        done();      }, 500);    });      grunt.registertask('express-keepalive', 'keep grunt running', function() {      this.async();    });      grunt.registertask('serve', function(target) {      if (target === 'dist') {        return grunt.task.run(['build', 'env:all', 'env:prod', 'express:prod', 'open', 'express-keepalive']);      }        if (target === 'debug') {        return grunt.task.run([          'clean:server',          'env:all',          'concurrent:server',          'injector',          'bowerinstall',          'autoprefixer',          'concurrent:debug'        ]);      }        grunt.task.run([        'clean:server',        'env:all',        'concurrent:server',        'injector',        'bowerinstall',        //  'autoprefixer',        'configureproxies:server',        'express:dev',        'wait',        'open',        'watch'      ]);    });      grunt.registertask('server', function() {      grunt.log.warn('the `server` task has been deprecated. use `grunt serve` start server.');      grunt.task.run(['serve']);    });      grunt.registertask('test', function(target) {      if (target === 'server') {        return grunt.task.run([          'env:all',          'env:test',          'mochatest'        ]);      } else if (target === 'client') {        return grunt.task.run([          'clean:server',          'env:all',          'concurrent:test',          'injector',          'autoprefixer',          'karma'        ]);      } else if (target === 'e2e') {        return grunt.task.run([          'clean:server',          'env:all',          'env:test',          'concurrent:test',          'injector',          'bowerinstall',          'autoprefixer',          'express:dev',          'protractor'        ]);      } else grunt.task.run([        'test:server',        'test:client'      ]);    });      grunt.registertask('build', [      'clean:dist',      'concurrent:dist',      'injector',      'bowerinstall',      'useminprepare',      'autoprefixer',      'ngtemplates',      'concat',      'ngmin',      'copy:dist',      'cdnify',      'cssmin',      'uglify',      'rev',      'usemin'    ]);      grunt.registertask('default', [      'newer:jshint',      'test',      'build'    ]);  };

code dir org

   app/     ├── client/     ├── server/     ├── setup/     └── uploads/     ├── bower.json     ├── e2e/     ├── error-log.txt     ├── gruntfile.js     ├── karma.conf.js     ├── node_modules/     ├── package.json     ├── protractor.conf.js     ├── readme.md 

it fact grunt-autoprefixer doesn't find files. if case block grunt:

https://github.com/ndmitry/grunt-autoprefixer/issues/115

my pr got merged , issue fixed in grunt-autoprefixer 3.0.3.