Avoid PHP warning by testing pseudo_bundles before iterating. (#732)

islandora.module

@@ -377,6 +377,7 @@ function islandora_entity_extra_field_info() {
 
   $pseudo_bundles = $config_factory->get(IslandoraSettingsForm::GEMINI_PSEUDO);
 
+  if (!empty($pseudo_bundles)) {
     foreach ($pseudo_bundles as $key) {
       list($bundle, $content_entity) = explode(":", $key);
       $extra_field[$content_entity][$bundle]['display']['field_gemini_uri'] = [
@@ -386,6 +387,7 @@ function islandora_entity_extra_field_info() {
         'visible' => TRUE,
       ];
     }
+  }
   return $extra_field;
 }