fix null reading getBoundingClientRect

enjoy/src/renderer/components/login-form.tsx

@@ -74,6 +74,7 @@ export const LoginForm = () => {
 
   useEffect(() => {
     if (!webviewUrl) return;
+    if (!containerRef?.current) return;
 
     EnjoyApp.view.onViewState((_event, state) => onViewState(state));
 

enjoy/src/renderer/pages/story-preview.tsx

@@ -170,6 +170,8 @@ export default () => {
     if (readable) {
       EnjoyApp.view.hide().catch(console.error);
     } else if (!loading) {
+      if (!containerRef?.current) return;
+
       const rect = containerRef.current.getBoundingClientRect();
       EnjoyApp.view.show({
         x: rect.x,