fix: Ignore CancellationException for running UI update tasks (#13708)

Ignore CancellationException if the task is cancelled in the meantime.
Authored-by: @HawkSK
Fixes #13610

Co-authored-by: @mshabarov

flow-server/src/main/java/com/vaadin/flow/server/VaadinService.java

@@ -38,6 +38,7 @@
 import java.util.Optional;
 import java.util.ServiceLoader;
 import java.util.Set;
+import java.util.concurrent.CancellationException;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.Future;
@@ -2059,6 +2060,10 @@ public void runPendingAccessTasks(VaadinSession session) {
                     try {
                         pendingAccess.get();
 
+                    } catch (CancellationException ignored) { // NOSONAR
+                        // Ignore canceled UI access tasks exceptions and don't
+                        // let it to be processed by the error handler and shown
+                        // on the UI
                     } catch (Exception exception) {
                         pendingAccess.handleError(exception);
                     }