commit 86b53f0d7abf802d584dc7e8e22ce49651c62870
Author: Alexandr Kirienko <alex@kirienko.net>
Date:   Sun May 10 23:18:22 2015 +0600

    #2463541-3

diff --git a/synonyms.module b/synonyms.module
index 58d30bd..a80ab57 100644
--- a/synonyms.module
+++ b/synonyms.module
@@ -361,14 +361,14 @@ function synonyms_get_term_by_synonym($name, $vocabulary, $parent = 0) {
 
     $result = $query->execute();
 
-    $term = reset($result['taxonomy_term']);
+    if (isset($result['taxonomy_term'])) {
+      $term = reset($result['taxonomy_term']);
 
-    if (isset($term->tid)) {
       return $term->tid;
     }
   }
 
-  if ($term = taxonomy_get_term_by_name($name, $vocabulary)) {
+  if ($term = taxonomy_get_term_by_name($name, $vocabulary->machine_name)) {
     return $term->tid;
   }