我正在尝试使用grunt运行角度项目，但是当我运行此命令grunt watch时，它会被警告中止。
Running "karma:unit" (karma) task
Warning: Cannot read property 'write' of null use --force to continue
Aborted due to warnings.
但是当我使用命令grunt watch --force时，我能够在浏览器中查看我的角度应用程序，但是在命令窗口中有错误说
Running "delta" task
Waiting...
D:\Projects\sampleweb\node_modules\karma\lib\logger.js:59
if (helper.isDefined(config.colors)) {
^
TypeError: Cannot read property 'colors' of null
at Object.setupFromConfig (D:\Projects\sampleweb\node_modules\karma\lib\log
ger.js:59:31)
at new Server (D:\Projects\sampleweb\node_modules\karma\lib\server.js:50:10
)
at ReadStream.<anonymous> (D:\Projects\sampleweb\node_modules\grunt-karma\l
ib\background.js:4:16)
at emitNone (events.js:106:13)
at ReadStream.emit (events.js:208:7)
at emitReadable_ (_stream_readable.js:513:10)
at emitReadable (_stream_readable.js:507:7)
at ReadStream.Readable.read (_stream_readable.js:384:7)
at ReadStream.Socket.read (net.js:362:43)
at nReadingNextTick (_stream_readable.js:797:8)
at _combinedTickCallback (internal/process/next_tick.js:135:11)
at process._tickCallback (internal/process/next_tick.js:180:9)
at Function.Module.runMain (module.js:686:11)
at startup (bootstrap_node.js:187:16)
at bootstrap_node.js:608:3
我无法弄清楚出了什么问题。我试图谷歌相同的错误，但找不到任何解决方案。
这是我的package.json文件。
{
"name": "sample pro",
"version": "2.10.3",
"author": "sample",
"devDependencies": {
"grunt": "~0.4.2",
"grunt-contrib-jshint": "^0.9.2",
"grunt-contrib-nodeunit": "~0.2.0",
"grunt-contrib-uglify": "~0.2.2",
"grunt-contrib-clean": "^0.5.0",
"grunt-contrib-copy": "^0.5.0",
"grunt-contrib-concat": "^0.3.0",
"grunt-contrib-watch": "^0.6.1",
"grunt-contrib-coffee": "^0.10.1",
"grunt-contrib-less": "^0.11.4",
"grunt-coffeelint": "0.0.8",
"grunt-html2js": "^0.2.4",
"grunt-ngmin": "0.0.3",
"grunt-express": "^1.4.1",
"karma": "^1.6.0",
"grunt-karma": "^0.12.2",
"karma-jasmine": "^0.1.5",
"karma-firefox-launcher": "^0.1.3",
"karma-chrome-launcher": "^0.1.3",
"karma-phantomjs-launcher": "^0.1.3",
"karma-coffee-preprocessor": "^0.2.1",
"lodash": "^2.4.1"
}
}