Unable to generate render.mjs or preload.mjs with valid source maps

[iongion]

Noticed these

• If I enable sourcemap: true or sourcemap: "inline" is just as if it was sourcemap: "hidden" for both.
• The generated chunks do not reference the sourcemap file anywhere (using the //# sourceMappingURL=${file}.map)

Wrote a plugin to inject the urls but now the sourcemaps don't match the code

function injectSourceMapURLPlugin() {
  const files: string[] = [];
  let outputBundle;
  return {
    name: "inject-source-map-url",
    writeBundle: (options, bundle) => {
      outputBundle = bundle;
    },
    closeBundle: () => {
      files.push(...Object.keys(outputBundle).filter((it) => !it.endsWith(".map")));
      console.debug("Bundle closed", outputBundle.code, files);
      files.forEach((file) => {
        const pathToSource = path.join(PROJECT_HOME, "build", file);
        const pathToSourceMap = path.join(PROJECT_HOME, "build", `${file}.map`);
        if (fs.existsSync(pathToSource) && fs.existsSync(pathToSourceMap)) {
          let contents = fs.readFileSync(pathToSource, "utf-8").toString();
          contents += `\n//# sourceMappingURL=${file}.map`;
          fs.writeFileSync(pathToSource, contents);
        }
      });
    }
  };
}

How do you guys enable sourcemaps, at least for development ?