Fix: JSX renderer "Hello world!" error (#822)

* fix: remove hello-world error

* chore: add changeset

.changeset/lovely-cats-sin.md

@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fix error when no renderers are passed

packages/astro/snowpack-plugin-jsx.cjs

@@ -83,9 +83,7 @@ Unable to resolve a renderer that handles JSX transforms! Please include a \`ren
 
         return {
           '.js': {
-            code: `(() => {
+            code: '',
-              throw new Error("Hello world!");
-            })()`,
           },
         };
       }