Fails when you pass the variables as an option and use a variable that doesn't exists.

[igor-ribeiro]

webpack config:

{
  loader: 'postcss-loader',
  options: {
    parser: 'postcss-scss',
    plugins: [
      require('postcss-cssnext')({
        features: {
          customProperties: false,
        },
      }),
      require('postcss-css-variables')({
        variables: {
          '--font': 'Arial',
        },
      }),
    ],
  },

CSS file:

body {
  color: var(--color);
}

Error:

Module build failed: TypeError: resultantValue.replace is not a function

Even with the preserve options it happens.

Is it a bug or it's the expected behavior?

[igor-ribeiro]

If I don't provide the variables option it outputs color: undefined.

[igor-ribeiro]

Never mind, my fault... One of the values was a number. It works as expected.