fix(scenarios): add error handling for API calls and dev script with local API

- add catch handler to promises for better error visibility
- use null coalescing operators to prevent undefined accessing
- add dev:compose-api npm script pointing to localhost:13000 API
- include toast dependency in useCallback to avoid stale closures

client/package.json

@@ -4,6 +4,7 @@
   "type": "module",
   "scripts": {
     "dev": "vite",
+    "dev:compose-api": "VITE_API_URL=http://localhost:13000/api/v1 vite",
     "build": "tsc -b && vite build",
     "preview": "vite preview",
     "storybook": "storybook dev -p 6006",

client/src/pages/scenario/ScenariosPage.tsx

@@ -37,11 +37,14 @@ export function ScenariosPage() {
   const load = useCallback(() => {
     Promise.all([scenarios.list(), environments.list(1, 200)])
       .then(([scenarioRes, envRes]) => {
-        setItems(scenarioRes.data);
+        setItems(scenarioRes?.data ?? []);
-        setEnvs(envRes.data);
+        setEnvs(envRes?.data ?? []);
+      })
+      .catch((err) => {
+        toast.error((err as Error).message);
       })
       .finally(() => setLoading(false));
-  }, []);
+  }, [toast]);
 
   useEffect(() => {
     load();