Fix commonjs entry in v6

.changeset/silver-lemons-sort.md

@@ -0,0 +1,5 @@
+---
+'preact-render-to-string': patch
+---
+
+Fix error in commonjs entry point

config/node-commonjs.js

@@ -1,21 +1,32 @@
 const fs = require('fs');
 const path = require('path');
+const assert = require('assert/strict');
 
 // This file will only export default exports in commonjs bundles
 // instead of guarding them behind a `.default` property.
 
 const filePath = (file) => path.join(process.cwd(), 'dist', file);
 
-// Main entry
-fs.copyFileSync(filePath('index.js'), filePath('commonjs.js'));
-fs.copyFileSync(filePath('index.js.map'), filePath('commonjs.js.map'));
-
-const source = `module.exports = require('./commonjs').default;`;
-fs.writeFileSync(filePath('index.js'), source, 'utf-8');
-
 // JSX entry
 fs.copyFileSync(filePath('jsx.js'), filePath('jsx-entry.js'));
 fs.copyFileSync(filePath('jsx.js.map'), filePath('jsx-entry.js.map'));
 
-const sourceJsx = `module.exports = require('./jsx-entry').default;`;
+const sourceJsx = [
+	`const entry = require('./jsx-entry');`,
+	`entry.default.render = entry.render;`,
+	`entry.default.shallowRender = entry.shallowRender;`,
+	`module.exports = entry.default;`
+].join('\n');
 fs.writeFileSync(filePath('jsx.js'), sourceJsx, 'utf-8');
+
+// Verify CJS entries
+const main = require(filePath('index.js'));
+assert(typeof main === 'function', 'Default export is a function');
+
+const jsx = require(filePath('jsx.js'));
+assert(typeof jsx === 'function', 'Default export is a function');
+assert(typeof jsx.render === 'function', 'render entry is a function');
+assert(
+	typeof jsx.shallowRender === 'function',
+	'shallowRender entry is a function'
+);