Warning: array_key_exists()

Hi there,

Firstly – love your work, such an awesome plugin 🙂 I am having a slight issue appear going through from the booking page to the reservation form:
Warning: array_key_exists() expects parameter 2 to be array, null given in /home/staidans01/staidansnorthcote.org.nz/wp-content/plugins/book-a-room/bookaroom-meetings-public.php on line 668

Don’t suppose you can tell what I’m doing wrong?

Also, I know other people have mentioned this but it would be so helpful to be able to edit form fields!