Invalid argument supplied for foreach() in getDerivatives when saving a profile

I believe we've seen something like this issue before, but in our case, when you save a profile, the following occurs:

Warning: Invalid argument supplied for foreach() in Drupal\Component\Plugin\Discovery\DerivativeDiscoveryDecorator->getDerivatives() (line 102 of core/lib/Drupal/Component/Plugin/Discovery/DerivativeDiscoveryDecorator.php).

The issue stems from ldap_authentication/src/Plugin/Derivative/DynamicUserHelpLink.php. The getDerivativeDefinitions() function will call $this->addLink(), but addlink() will set $definitions to NULL (instead of an array) if the following "if" cannot be satisfied:

if (\Drupal::config('ldap_authentication.settings')
      ->get('ldapUserHelpLinkText') && \Drupal::config('ldap_authentication.settings')
      ->get('ldapUserHelpLinkUrl')) { ... }

A simple fix is to return $this->derivatives after the if() rather than inside it.

--- ldap_authentication/src/Plugin/Derivative/DynamicUserHelpLink.php.orig
+++ ldap_authentication/src/Plugin/Derivative/DynamicUserHelpLink.php
@@ -74,8 +74,8 @@
       $this->derivatives['ldap_authentication.show_user_help_link']['title'] = \Drupal::config('ldap_authentication.settings')
         ->get('ldapUserHelpLinkText');
       $this->derivatives['ldap_authentication.show_user_help_link']['route_name'] = 'ldap_authentication.ldap_help_redirect';
-      return $this->derivatives;
     }
+    return $this->derivatives;
   }

 }