Check variables before using

We see such error log:

PHP Notice：Undefined index: options_source in _webform_select_options()

and it occurs in DRUPAL_BASE/modules/webform/components/select.inc (line# 915).

Here is the patch :

--- webform/components/select.inc.orig 2016-08-09 17:48:08.008654463 +0800
+++ webform/components/select.inc 2016-08-09 17:48:22.374654268 +0800
@@ -912,7 +912,7 @@
* Generate a list of options for a select list.
*/
function _webform_select_options($component, $flat = FALSE, $filter = TRUE) {
- if ($component['extra']['options_source']) {
+ if (@$component['extra']['options_source']) {
$options = _webform_select_options_callback($component['extra']['options_source'], $component, $flat);
}
else {