I am having trouble with the previous_post_link() and next_post_link() functionality. When there is no previous post, the function previous_post_link() does not display a link, likewise for the next_post_link() and the last post. I would like to have a placeholder image so that the design stays consistent.

Currently I have images of green arrows pointing left and right, I would like to place an image of a grey arrow if there are no more posts to go back to.

Is there a way to use the next_post_link()/previous_post_link() functions but not have the link removed.

I also wonder if there is a way for the links to cycle, so that if you come to the most recent post, the next post link would bring you back to the first post.