90ce96a regression

https://bitbucket.org/cornershopcreative/wp-popup/commits/90ce96afd47633107d4207e7dd1fbf9cb2e3f00b

This commit introduced a disable_single_post function hook’ed into pre_get_posts.
This function makes use of is_singular which, at this stage is not usable (because get_posts didn’t finished and as such can’t determine the type of the current page).

This trigger this problem:
Trying to get property 'post_type' of non-object in /wp/wp-includes/class-wp-query.php on line 4147
from is_singular( ) at class-wp-popup.php:807

The page I need help with: [log in to see the link]