Add text in case no data is shown in timetracking overview (#7736)

* add text in case no data is shown in timetracking overview

* add changelog

* lint

CHANGELOG.unreleased.md

@@ -27,6 +27,7 @@ For upgrade instructions, please check the [migration guide](MIGRATIONS.released
 - Fixed incorrect position of WEBKNOSSOS logo in screenshots. [#7726](https://github.com/scalableminds/webknossos/pull/7726)
 - Fixed that invisible nodes could be selected when using the skeleton tool. [#7732](https://github.com/scalableminds/webknossos/pull/7732)
 - Fixed a bug where users that have no team memberships were omitted from the user list. [#7721](https://github.com/scalableminds/webknossos/pull/7721)
+- Added an appropriate placeholder to be rendered in case the timetracking overview is otherwise empty. [#7736](https://github.com/scalableminds/webknossos/pull/7736)
 
 ### Removed
 

frontend/javascripts/admin/statistic/time_tracking_overview.tsx

@@ -113,6 +113,15 @@ function TimeTrackingOverview() {
     { label: "Last 30 Days", value: [dayjs().subtract(30, "d").startOf("day"), currentTime] },
   ];
 
+  const renderPlaceholder = () => {
+    return (
+      <p>
+        There is no user activity recorded for the selected time span. Please adjust the time range
+        and filters above.
+      </p>
+    );
+  };
+
   return mayUserAccessView ? (
     <Card
       title={"Annotation Time per User"}
@@ -169,6 +178,9 @@ function TimeTrackingOverview() {
             marginBottom: 30,
           }}
           pagination={false}
+          locale={{
+            emptyText: renderPlaceholder(),
+          }}
         >
           <Column
             title="User"