webpack 打包js出错

webpack.config.js代码

var path = require('path');
var webpack = require('webpack');

var distPath = path.join(__dirname, '/public/dist/');

module.exports = {
    entry: {
        a: './components/a.js',
        b: './components/b.js'
    },
    output: {
        path: distPath,
        publicPath: "/public/dist/",
        filename: '[name].js'
    }
    //plugins: plugins
};

a.js代码

require("c.js");

b.js代码

require("c.js");

c.js代码

var c = function(){
    console.log('asdasd');
}

module.exports = c;

错误提示

Hash: 7d501d0a5c06770cc551
Version: webpack 1.13.1
Time: 47ms
Asset     Size  Chunks             Chunk Names
 a.js  1.57 kB       0  [emitted]  a
 b.js  1.57 kB       1  [emitted]  b
    + 2 hidden modules

ERROR in ./components/b.js
Module not found: Error: Cannot resolve module 'c.js' in D:\luoo\nodejs\components
 @ ./components/b.js 1:0-15

ERROR in ./components/a.js
Module not found: Error: Cannot resolve module 'c.js' in D:\luoo\nodejs\components
 @ ./components/a.js 1:0-15

我想问为什么会有错误提示？
经验证发现如果 require 的不是路径而是用别名的方式就不会有错误提示。
求解惑！

---

写相对路径

require("./c.js");