Issue #1910596 by ytsurk: markup issues: w3c validation

theme/entity.theme.inc

@@ -201,8 +201,12 @@ function template_preprocess_entity(&$variables) {
 
   // Add RDF type and about URI.
   if (module_exists('rdf')) {
-    $variables['attributes_array']['about'] = empty($uri['path']) ? NULL: url($uri['path']);
-    $variables['attributes_array']['typeof'] = empty($entity->rdf_mapping['rdftype']) ? NULL : $entity->rdf_mapping['rdftype'];
+    if (!empty($uri['path'])) {
+      $variables['attributes_array']['about'] = url($uri['path']);
+    }
+    if (!empty($entity->rdf_mapping['rdftype'])) {
+      $variables['attributes_array']['typeof'] = $entity->rdf_mapping['rdftype'];
+    }
   }
 
   // Add suggestions.