SqlResultProvider fetchField - check for empty result

Model/SqlResultProvider.php

@@ -101,7 +101,12 @@ class SqlResultProvider implements iSqlResultItems
      */
     public function fetchField($field)
     {
-        return $this->result->fetchField($field);
+        if ($this->result->numRows())
+        {
+            return $this->result->fetchField($field);
+        } else {
+            return false;
+        }
     }
 
     /**