Plugin.registerCompiler({ extensions: ['js', 'jsx', 'mjs'], }, function () { return new BabelCompiler({ react: true }, (babelOptions, file) => { if (file.hmrAvailable() && ReactFastRefresh.babelPlugin) { babelOptions.plugins = babelOptions.plugins || []; babelOptions.plugins.push(ReactFastRefresh.babelPlugin); } }); });