fix(app-render): handle optional model in renderApp function

ui/src/ui/app-render.ts

@@ -767,7 +767,10 @@ export function renderApp(state: AppViewState) {
                     Array.isArray(list) && list[index]
                       ? (list[index] as { model?: unknown })
                       : null;
-                  const existing = entry.model;
+                  const existing = entry?.model;
+                  if (!existing) {
+                    return;
+                  }
                   const resolvePrimary = () => {
                     if (typeof existing === "string") {
                       return existing.trim() || null;