Issue #3259009: PHP Warnings/Notices on Download Page

src/Element/AutoExportExcludedColumns.php

@@ -60,10 +60,10 @@ class AutoExportExcludedColumns extends WebformExcludedBase {
         // Skip this validation if download button triggered or
         // save settings button without a tick to update auto CSV export settings checkbox
         $triggering_element = $form_state->getTriggeringElement();
-        if (empty($triggering_element['#submit']) || $form_state->getValue(update_auto_export_configs) == 0) {
+        if (empty($triggering_element['#submit']) || $form_state->getValue('update_auto_export_configs') == 0) {
             return;
         }
-        if ($element['#multiple']) {
+        if (isset($element['#multiple'])) {
             if (!is_array($element['#value']) || !count(array_filter($element['#value']))) {
                 $form_state
                     ->setError($element, t('No items selected.'));