Set the console error panic hook

Turn on the browser console panic message output provided by the
`console_error_panic_hook` feature. This feature was already enabled by
default in our Cargo configuration, but it wasn't actually being used.

app-proto/src/main.rs

@@ -46,6 +46,10 @@ impl AppState {
 }
 
 fn main() {
+    // set the console error panic hook
+    #[cfg(feature = "console_error_panic_hook")]
+    console_error_panic_hook::set_once();
+    
     sycamore::render(|| {
         provide_context(AppState::new());