Webpack configuration file found but no entry configured

Im trying to organize a webpack 2 template for my personal projects with webpack-dev-server and run it with the npm commands, but i'm getting this error:

Configuration file found but no entry configured.

It's weird because the entry is defined and i tested the resolved route, it's fine, so here is my webpack config, the command to run it and the file to configure the loaders:

webpack.config.dev.js

const path       = require('path');
const fs         = require('fs');
const configs    = require('./dev-wpk-conf');
const HtmlPlugin = require('html-webpack-plugin');
const Dotenv     = require('dotenv-webpack');
const webpack    = require('webpack');
const dirPath    = fs.realpathSync(process.cwd());

const config = {
  entry: {
    bundle: path.resolve(dirPath, '../src/index.js'),
    vendor: configs.vendor
  },
  output: {
    path: path.resolve(dirPath, '../dist'),
    filename: '[name].[hash].js'
  },
  devServer: {
    port: 3030
  },
  module: {
    rules: [
      configs.jsonLoader,
      configs.babelLoader,
      configs.imgLoader,
      configs.sassLoader
    ]
  },
  plugins: [
    new webpack.optimize.CommonsChunkPlugin({ names: ['vendor', 'manifest'] }),
    new HtmlPlugin({ template: './src/index.html' }),
    new Dotenv()
  ]
}

dev-wpk-conf.js (the loaders):

const vendor = [
  'react',
  'react-dom',
  'react-redux',
  'react-router',
  'redux',
  'redux-form',
  'redux-thunk',
  'redux-devtools-extension'
];

const jsonLoader = {
  test: /\.json$/,
  loader: 'json-loader'
};

const babelLoader = {
  test: /\.js$/,
  loader: 'babel-loader',
  exclude: /node_modules/,
  options: {
    presets: ['babel-preset-env', 'react']
  }
};

const imgLoader = {
  test: /\.(jpe?g|png|gif|svg)$/,
  use: [
    { loader: 'url-loader', options: { limit: 40000 } },
    'image-webpack-loader'
  ]
};

const sassLoader = {
  test: /\.(scss|sass)$/,
  use: [
    { loader: 'css-loader' },
    { loader: 'sass-loader' }
  ],
  fallback: 'style-loader'
};

module.exports = {
  vendor,
  jsonLoader,
  babelLoader,
  imgLoader,
  sassLoader
};

NPM scripts:

"clean": "rimraf dist",
"serve": "yarn clean && webpack-dev-server --config ./config/webpack.config.dev.js"

The folder structure:

config/
    dev-wpk-conf.js
    prod-wpk-conf.js
    webpack.config.dev.js
    webpack.config.prod.js
node_modules/
    ...
src/
    index.js
    // the app code
package.json
.env
//rc files

So, why exactly i'm getting this error? I'm not an expert but the entry is defined and the resolved path (again) is correct.

Any hint?

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