fix: Source maps in export-default-simplify plugin

package.json

@@ -97,6 +97,7 @@
 		"gzip-size": "^6.0.0",
 		"kleur": "^4.1.5",
 		"lodash.merge": "^4.6.2",
+		"magic-string": "^0.30.17",
 		"postcss": "^8.2.1",
 		"pretty-bytes": "^5.6.0",
 		"rollup": "^2.70.2",

src/index.js

@@ -39,6 +39,7 @@ import {
 import { getConfigFromPkgJson, getName } from './lib/package-info';
 import { shouldCssModules, cssModulesConfig } from './lib/css-modules';
 import { EOL } from 'os';
+import MagicString from 'magic-string';
 
 // Extensions to use when resolving modules
 const EXTENSIONS = ['.ts', '.tsx', '.js', '.jsx', '.es6', '.es', '.mjs'];
@@ -599,15 +600,17 @@ function createConfig(options, entry, format, writeMeta) {
 					({
 						name: 'export-default-simplify',
 						renderChunk(code, chunk, options) {
-							let out = code.replace(
+							const s = new MagicString(code);
+							s.replace(
 								/([};\n])export\s*\{\s*([a-zA-Z0-9_$]+)\s+as\s+default\s*\};/,
 								(s, before, name) => {
 									return `${before}export default ${name};`;
 								},
 							);
-							if (out !== code) {
-								return { code: out, map: null };
-							}
+							return {
+								code: s.toString(),
+								map: s.generateMap({ hires: true }),
+							};
 						},
 					}),
 					options.compress !== false && [