fix: Do not throw if re-setting the login view (#19996) (#20003)

Fixes #19910

Co-authored-by: Artur <[email protected]>

flow-server/src/main/java/com/vaadin/flow/server/auth/NavigationAccessControl.java

@@ -187,6 +187,10 @@ public final boolean isEnabled() {
      *            the Flow view to use as login view
      */
     public final void setLoginView(Class<? extends Component> loginView) {
+        if (loginView == this.loginView) {
+            // Probably hot reload
+            return;
+        }
         throwIfLoginViewSet();
         this.loginView = loginView;
     }
@@ -210,6 +214,11 @@ protected Class<? extends Component> getLoginView() {
      *            the frontend view to use as login view
      */
     public void setLoginView(String loginUrl) {
+        if (loginUrl == this.loginUrl) {
+            // Probably hot reload
+            return;
+        }
+
         throwIfLoginViewSet();
         this.loginUrl = loginUrl;
     }