How to write plugin that adds resolve.extensions when it is not defined in config?

[krutoo]

Hi, im trying to write simple plugin that adds extensions in configuration.

I write this logic in my plugin:

compiler.hooks.afterEnvironment.tap('MyPlugin', () => {
  if (!compiler.options.resolve.extensions) {
    compiler.options.resolve.extensions = ['...'];
  }

  const { extensions } = compiler.options.resolve;

  for (const ext of ['.ts', '.tsx']) {
    if (!extensions.includes(ext)) {
      extensions.push(ext);
    }
  }
});

Its working only when extensions provided in configuration object. Even if empty array is provided.

It is not working if resolve.extensions is not defined.

Is it bug or do I something wrong?

[krutoo]

The detailed answer for same question in Webpack is here:
webpack/webpack#19170 (comment)

It is works for Rspack too