Bug with the refactored AssetSourceGenerator in 5.96.0

[titouanmathis]

Bug report

What is the current behavior?

When using the html-webpack-plugin with a loader to transform its templates, I get the following error :

Error: The loader "/path/to/index.html" didn't return html.

If the current behavior is a bug, please provide the steps to reproduce.

See https://github.com/titouanmathis/repro-webpack-html-plugin-asset-source-regression for a reproduction.

This seems to be a Webpack regression, so I have not yet opened an issue in the html-webpack-plugin repository.

The reproduction repository contains a patch, but I am not sure if it is the best way to fix this regression.

I was able to identify a7e5e6a as the first bad commit with git bisect.

What is the expected behavior?

The loader should be applied and return the transformed content instead of an empty string.

Other relevant information:
webpack version: 5.96.0
Node.js version: 22
Operating System: macOS
Additional tools: html-webpack-plugin

[alexander-akait]

#18928

[alexander-akait]

So this is the expected result, use type: "javascript/auto" instead type: "asset/source"

[titouanmathis]

Thanks for the quick response, I missed the existing issue when searching for my error. I will update the loader on my end.

Sorry for the noise.

[alexander-akait]

I forget to write code for loader:

export default function loader(source) {
  return 'export default ' + JSON.stringify(source);
}

[alexander-akait]

 {
    test: /\.html/,
    type: 'javascript/auto',
    loader: './loaders/html.js',
  },