Fix: Every variable in the chat settings is required. (#17727)

web/src/pages/next-chats/chat/app-settings/dynamic-variable.tsx

@@ -33,7 +33,7 @@ export function DynamicVariableForm({
 
   const add = useCallback(() => {
     append({
-      key: undefined,
+      key: '',
       optional: false,
     });
   }, [append]);

web/src/pages/next-chats/chat/app-settings/use-chat-setting-schema.tsx

@@ -26,7 +26,7 @@ export function useChatSettingSchema() {
     parameters: z
       .array(
         z.object({
-          key: z.string(),
+          key: z.string().min(1, { message: t('variableKeyMessage') }),
           optional: z.boolean(),
         }),
       )