strtotime(): Passing null to parameter #1. Fixed.

admin/users.php

@@ -114,7 +114,11 @@ function can_process($new) {
 	alt_table_row_color($k);
 
 	$time_format = (user_date_format() == 0 ? 'h:i a' : 'H:i');
-	$last_visit_date = sql2date($myrow['last_visit_date']).' '.date($time_format, strtotime($myrow['last_visit_date']));
+
+	if(empty($myrow['last_visit_date']))
+		$last_visit_date = '';
+	else
+		$last_visit_date = sql2date($myrow['last_visit_date']).' '.date($time_format, strtotime($myrow['last_visit_date']));
 
 	/*The security_headings array is defined in config.php */
 	$not_me = strcasecmp($myrow['user_id'], $_SESSION['wa_current_user']->username);
@@ -196,4 +200,4 @@ function can_process($new) {
 submit_add_or_update_center($selected_id == -1, '', 'both');
 
 end_form();
-end_page();
+end_page();