Account for the possibility that there is no profile installed

See https://www.drupal.org/node/3432357.

Closes to #3460077

lightning_core.install

@@ -14,14 +14,18 @@ function lightning_core_requirements() {
   $requirements = [];
 
   $profile = Drupal::installProfile();
-  $profile = Drupal::service('extension.list.profile')->get($profile);
+  
+  if ($profile) {
+    $profile = Drupal::service('extension.list.profile')->get($profile);
 
-  if (isset($profile->info['base profile'])) {
-    $requirements['lightning_core_base_profile'] = [
-      'title' => t('Base profile'),
-      'value' => $profile->info['base profile'],
-    ];
+    if (isset($profile->info['base profile'])) {
+      $requirements['lightning_core_base_profile'] = [
+        'title' => t('Base profile'),
+        'value' => $profile->info['base profile'],
+      ];
+    }
   }
+
   return $requirements;
 }