fix(sveltekit): Remove invalid return in fetch proxy script (#8835)

Fixes a bug where we incorrectly returned from the sveltekit fetch proxy Html script.

Author: Lms24

packages/sveltekit/src/server/handle.ts

@@ -59,9 +59,10 @@ function sendErrorToSentry(e: unknown): unknown {
 
 const FETCH_PROXY_SCRIPT = `
     const f = window.fetch;
-    if(!f){return}
-    window._sentryFetchProxy = function(...a){return f(...a)}
-    window.fetch = function(...a){return window._sentryFetchProxy(...a)}
+    if(f){
+      window._sentryFetchProxy = function(...a){return f(...a)}
+      window.fetch = function(...a){return window._sentryFetchProxy(...a)}
+    }
 `;
 
 export const transformPageChunk: NonNullable<ResolveOptions['transformPageChunk']> = ({ html }) => {