fix: stop the dev toolbar from reporting benign ResizeObserver loop

.changeset/tricky-goats-cheer.md

@@ -0,0 +1,5 @@
+---
+"@solidjs/start": patch
+---
+
+Stop the dev toolbar from reporting benign `ResizeObserver loop` notifications as application errors. Browsers dispatch these as window `error` events carrying no error object, so the toolbar was capturing the raw `ErrorEvent` and force-opening the error panel over the app on every resize.

packages/start/src/shared/dev-toolbar/index.tsx

@@ -157,6 +157,11 @@ export function DevToolbar(props: DevToolbarProps) {
 
   createEffect(() => {
     const onErrorEvent = (error: ErrorEvent) => {
+      // Browsers dispatch benign ResizeObserver loop notifications as window
+      // "error" events carrying no error object. They aren't app errors.
+      if (!error.error && error.message?.startsWith("ResizeObserver loop")) {
+        return;
+      }
       pushError(error.error ?? error);
     };