Only allow .render targets to run reactExtension (#2498)

Merge pull request #2498 from Shopify/bs/fix-reactExtension

Author: belalsj

.changeset/neat-paws-smile.md

@@ -0,0 +1,5 @@
+---
+'@shopify/ui-extensions-react': patch
+---
+
+surfaces/admin: the reactExtension will only allow .render targets to run

packages/ui-extensions-react/src/surfaces/admin/render.tsx

@@ -34,6 +34,12 @@ export function reactExtension<ExtensionTarget extends RenderExtensionTarget>(
   // Playground extension, since all render extensions have the same general
   // shape (`RenderExtension`).
   return extension<'Playground'>(target as any, async (root, api) => {
+    if (!target.match(/\.render$/)) {
+      throw new Error(
+        `reactExtension can only be used for .render extension targets, got: ${target}`,
+      );
+    }
+
     const element = await render(api as ApiForRenderExtension<ExtensionTarget>);
 
     return remoteRootRender(