WP_Widget errors now in sage

sage
2

Use \WP_Widget, or put use WP_Widget; at the top of the file.

See:

http://php.net/manual/en/language.namespaces.faq.php#language.namespaces.faq.shouldicare

Related thread:

https://discourse.roots.io/t/class-roots-sage-wp-query-not-found/2967