我已经在我的 yeoman 项目中全局和本地安装了 grunt，但是所有 grunt 命令都会给出以下错误。知道如何解决这个问题吗？
c:\wip\code\project\yo>grunt -v
Initializing
Command-line options: --verbose
c:\wip\code\project\yo\node_modules\grunt\lib\grunt\file.js:372
return fs.existsSync(filepath);
^
TypeError: Object #<Object> has no method 'existsSync'
at Object.exists (c:\wip\code\project\yo\node_modules\grunt\lib\grunt\fil
e.js:372:13)
at Task.init (c:\wip\code\project\yo\node_modules\grunt\lib\grunt\task.js
:417:31)
at Object.tasks (c:\wip\code\project\yo\node_modules\grunt\lib\grunt.js:1
13:8)
at Object.cli (c:\wip\code\project\yo\node_modules\grunt\lib\grunt\cli.js
:38:9)
at Object.<anonymous> (C:\Users\me\AppData\Roaming\npm\node_modules\
grunt-cli\bin\grunt:41:20)
at Module._compile (module.js:446:26)
at Object..js (module.js:464:10)
at Module.load (module.js:353:31)
at Function._load (module.js:311:12)
at Array.0 (module.js:484:10)