feat: enhance layout and sidebar functionality with new PageHeader and SidebarContext

src/pages/RegisterPage.tsx

@@ -33,7 +33,9 @@ export function RegisterPage() {
     const loadProviders = async () => {
       try {
         const providers = await authService.getOAuthProviders()
-        setOauthProviders(providers)
+        if (providers) {
+          setOauthProviders(providers)
+        }
       } catch (error) {
         console.error('Failed to load OAuth providers:', error)
       }