If the level box remains empty while searching for the map, it crashes the application. This is because the search button attempts to parse a number from the textbox, and if the textbox is not a number, the attempt throws an uncaught exception resulting in a crash. A fix would be to validate the textbox as only containing an integer between 1-100, and possibly falling back on TryParse, which does not throw exceptions.
If the level box remains empty while searching for the map, it crashes the application. This is because the search button attempts to parse a number from the textbox, and if the textbox is not a number, the attempt throws an uncaught exception resulting in a crash. A fix would be to validate the textbox as only containing an integer between 1-100, and possibly falling back on TryParse, which does not throw exceptions.