2018-10-06 UTC
# 
Zegnat GWG, set_headers doesn’t do any validation (https://github.com/WordPress/WordPress/blob/da7a80d67fea29c2badfc538bfc01c8a585f0cbe/wp-includes/class-wp-http-response.php#L74-L76) so theoretically get_headers could return something that isn’t an array. Though I am having a hard time seeing where the response object is actually getting created, or what could affect it.