Notice: Undefined offset: 0 in eval() (line 2 of computed_field.module

My content type contains a field collection which contains a computed field. When I add additional instances of the field collection to the node, I get the following error appearing at the top of the page:

Notice: Undefined offset: 0 in eval() (line 2 of /var/www/mainweb-current/sites/all/modules/computed_field/computed_field.module(466) : eval()'d code).