update list tile

lib/list_tile/as_list_tile.dart

@@ -61,7 +61,9 @@ class _ASListTileState extends State<ASListTile> {
             ),
           ),
           Expanded(
-            child: widget.text is String
+            child: widget.text == null
+                ? Text('')
+                : widget.text is String
                     ? Text(
                         widget.text,
                         maxLines: 2,