probably fixed blank page issue upon logout

frontend/src/App.svelte

@@ -3,7 +3,7 @@
     import { Router, Route } from 'svelte-tiny-router';
 
     import { loadTranslation } from './translations.svelte.js';
-    import { user } from './user.svelte.js';
+    import { checkUser, user } from './user.svelte.js';
 
     import AddDoc      from "./routes/document/Add.svelte";
     import AddTask     from "./routes/task/Add.svelte";
@@ -46,12 +46,17 @@
         fetch(url).then(resp => resp.text()).then(css => document.getElementById('usercss').innerText = css);
     }
 
+    async function testGuard({to, from, next}){
+        await checkUser();
+        next();
+    }
+
     $effect(() => loadTheme(user.theme));
 </script>
 
 {#if translations_ready }
-    <Router>
-    {#if user.name }
+    {#if user.name}
+        <Router beforeEach={[testGuard]}>
         <!-- https://github.com/notnotsamuel/svelte-tiny-router -->
         <Menu />
         <Route path="/"                            component={User} />
@@ -85,14 +90,16 @@
         <Route>
             Not found!
         </Route>
+        </Router>
     {:else}
+        <Router>
         <Route path="/user/reset/pw" component={ResetPw} />
         <Route path="/oidc_callback" component={Callback} />
         <Route>
             <Login />
         </Route>
+        </Router>
     {/if}
-    </Router>
     <Footer />
 {:else}
     <p>Loading translations...</p>