patch import_unsupported definition

Author: dario-piotrowicz

packages/cloudflare/src/cli/build/build-worker.ts

@@ -133,6 +133,24 @@ globalThis.__dangerous_ON_edge_converter_returns_request = true;
   console.log(`\x1b[35mWorker saved in \`${workerOutputFile}\` 🚀\n\x1b[0m`);
 }
 
+/**
+ * Next.js sets this `__import_unsupported` on `globalThis`:
+ * https://github.com/vercel/next.js/blob/5b7833e3/packages/next/src/server/web/globals.ts#L94-L98
+ *
+ * For some reason on us this gets run more than once causing a `Cannot redefine property: __import_unsupported`
+ * runtime error.
+ *
+ * So here we patch the function to only define the property if it is not already there
+ *
+ * TODO: this should ideally be done in a more robust way with ts-morph
+ */
+export function patchEnhanceGlobals(code: string) {
+  return code.replace(
+    `Object.defineProperty(globalThis, "__import_unsupported",`,
+    `if(!("__import_unsupported" in globalThis)) Object.defineProperty(globalThis, "__import_unsupported",`
+  );
+}
+
 /**
  * This function applies string replacements on the bundled worker code necessary to get it to run in workerd
  *
@@ -154,6 +172,7 @@ async function updateWorkerBundledCode(workerOutputFile: string, config: Config)
   patchedCode = await patchCache(patchedCode, config);
   patchedCode = inlineMiddlewareManifestRequire(patchedCode, config);
   patchedCode = patchExceptionBubbling(patchedCode);
+  patchedCode = patchEnhanceGlobals(patchedCode);
 
   await writeFile(workerOutputFile, patchedCode);
 }