Unable to create dynamic group operations

Problem/Motivation

In case there are no links showing up for a particular role (based on group permissions), you cannot create any new links dynamically using hook_group_operations_alter

Steps to reproduce

1. Create a group type and a group of that type
2. Login with a role with no permissions for the group (easiest might be as anonymous/logged out)
3. Add the following hook (change the hook with module name and the role check depending on the previous point)
   

   function hook_group_operations_alter(array &$operations, GroupInterface $group) {
       // Make sure there is a button to direct anonymous users to login page
       if (\Drupal::currentUser()->isAnonymous()) {
         $operations['group-login-join'] = [
             'title' => 'Login To Join',
             'url' => new Url('user.login'),
             'weight' => -1
         ];
       }
   }
   

4. Go to the group page
5. You will not see the "Login To Join" button

Proposed resolution

/src/Plugin/Block/GroupOperationsBlock.php's build() function calls $this->moduleHandler->alter('group_operations', $links, $group); only if $links is not empty. This should be called outside the if condition. See the patch attached.