Stop ignoring errors inside vue.config

[neves]

If I create a vue.config.js like this:

const webpack = require('webpack')
module.exports = {
  title: 'todo',
  resolve: true,
  open: false,
  plugins: [
    new webpack.DefinePlugin({
      VERSION: '"1.2.3"'
    })
  ]
}

It will fail to load config when webpack is not a dependency and vbuild is running globally as usual.
That's because it will raise a MODULE_NOT_FOUND error that is miss interpreted as config file not found, and nothing is printed.
This pull request try to fix that, but keep the default behavior to support .js and .json config files.

Please, let me know if I need to better explain myself

[egoist]

we have path-exists installed, we can use that

[egoist]

never mind, I'll fix this

[egoist]

the configFilePath may have extension, should stop adding extension if it already ends with .js or .json

[egoist]

Oops, I see, we don't need to check this.

[egoist]

damn, I accidentally clicked approved changes button 😐

[egoist]

maybe we can use something like:

const existingConfigFilePath = yield Promise
  .all(['', '.js', '.json'].map(ext => pathExists(`${configFilePath}${ext}`)))
  .then(result => getExistingFilePath(result))

fileConfig = require(existingConfigFilePath)

Could be faster?

[neves]

I'm not sure if for just 3 sync calls, this async solution would be faster enough to justify that complexity.