Fix sfDoctrineTester, string cannot be accessed as array

Author: Tybaze

lib/plugins/sfDoctrinePlugin/lib/test/sfTesterDoctrine.class.php

@@ -65,7 +65,7 @@ public function check($model, $query, $value = true)
         }
 
         $operator = '=';
-        if ('!' == $condition[0])
+        if (strlen($condition) && '!' == substr($condition,0,1))
         {
           $operator = false !== strpos($condition, '%') ? 'NOT LIKE' : '!=';
           $condition = substr($condition, 1);
@@ -103,7 +103,7 @@ public function check($model, $query, $value = true)
 
   /**
    * Outputs some debug information about queries run during the current request.
-   * 
+   *
    * @param integer|string $limit Either an integer to return the last many queries, a regular expression or a substring to search for
    */
   public function debug($limit = null)