Problematic plugin

Notice: Undefined index: post_type in /wp-content/plugins/simple-content-construction-kit/wp-simple-cck.php on line 132
Notice: Undefined index: post_type in /wp-content/plugins/simple-content-construction-kit/wp-simple-cck.php on line 134
Notice: Undefined variable: post in /wp-content/plugins/simple-content-construction-kit/wp-simple-cck.php on line 137
Notice: Trying to get property of non-object in /wp-content/plugins/simple-content-construction-kit/wp-simple-cck.php on line 141
Notice: Trying to get property of non-object in /wp-content/plugins/simple-content-construction-kit/wp-simple-cck.php on line 142

This is the code:

function parent_menu_header() {
   global $wp_query,$wpdb;
   $post_type = $wp_query->query_vars['post_type'];
  	if(!$post_type) {
  		$post_type = $_REQUEST['post_type'];
  	}
  	if(!$post_type) {
  		$post_type =get_post_type( $post ) 	;
  	}

   $row = $wpdb->get_row("select * from ".$wpdb->prefix."scck_content_type where  	product_machine_name = '$post_type'");
  	$lbl = $row->menu_label;
   $row_menu_id = $row->menu_id;
  	$id = "toplevel_page_cck-main-".$row_menu_id;
  	if($post_type) {

  ?>