print something when there is nothing

front/src/components/Posts.tsx

@@ -28,6 +28,11 @@ export function Posts(props: PostsProps) {
                         </li>
                 )
             }
+            {
+                props.rows.length == 0
+                    ? <pre>empty!</pre>
+                    : null
+            }
         </ul>
     );
 }

front/src/pages/index.tsx

@@ -94,7 +94,7 @@ export function Index() {
                 {
                     data
                         ? <Posts rows={data.filter(x => selected ? selected?.indexOf(x) === -1 : true)} onSelectChange={select} />
-                        : <></>
+                        : <pre>no data!</pre>
                 }
             </InfiniteScroller>
         </div>