make sure that ReactDevToolsBackend ends up in the global scope

Author: fullstackhacker

packages/react-devtools-core/src/standalone.js

@@ -384,14 +384,19 @@ function startServer(
     const clientUseHttps = clientOptions?.useHttps ?? useHttps;
 
     response.end(
-      backendFile.toString() +
+      // The backend UMD bundle may not assign to the global scope if the
+      // environment leaks `exports` or `module` (e.g. bundled apps, webviews).
+      // Wrap it so we always capture the export.
+      `(function() {\n` +
+        `var exports = undefined, module = undefined, define = undefined;\n` +
+        backendFile.toString() +
         '\n;' +
-        `ReactDevToolsBackend.initialize(undefined, undefined, undefined, ${componentFiltersString});` +
-        '\n' +
-        `ReactDevToolsBackend.connectToDevTools({port: ${clientPort}, host: '${clientHost}', useHttps: ${
+        `var Backend = typeof ReactDevToolsBackend !== "undefined" ? ReactDevToolsBackend : self.ReactDevToolsBackend;\n` +
+        `Backend.initialize(undefined, undefined, undefined, ${componentFiltersString});\n` +
+        `Backend.connectToDevTools({port: ${clientPort}, host: '${clientHost}', useHttps: ${
           clientUseHttps ? 'true' : 'false'
-        }${path != null ? `, path: '${path}'` : ''}});
-        `,
+        }${path != null ? `, path: '${path}'` : ''}});\n` +
+      `})();\n`,
     );
   });