Subtract overflow in Pad Height

[Joymfl]

Hey there, this is my first time posting an issue! I forked the repo and tried to use cargo run on it but it threw a Subtract with Overflow error. So, it turns out in ui.rs the mine_rect.height is < grid_height. I fixed it by having a default value of 10 as such: let vertical_pad_block_height = block_height(mines_rect.height, grid_height).unwrap_or(10); I know this isn't the best way to solve it and I'd love to learn how to make better ones. I'd really appreciate feedback on how to improve on submitting issues too.