PHP Fatal error on Pressable site with Jetpack beta

[rachelsquirrel]

There's a server error 500 on my Pressable site - http://rachelsquirrel.mystagingwebsite.com

This is in the debug.log

[18-Nov-2016 14:29:11 UTC] PHP Fatal error:  Uncaught Error: Call to a member function using_index_permalinks() on null in /rachelsquirrel/wp-content/plugins/jetpack-pressable-beta/jetpack.php:41
Stack trace:
#0 /wordpress/core/4.6.1/wp-includes/plugin.php(235): jetpack_index_permalinks_rest_api_url('wp-json')
#1 /wordpress/core/4.6.1/wp-includes/rest-api.php(168): apply_filters('rest_url_prefix', 'wp-json')
#2 /rachelsquirrel/wp-content/plugins/woocommerce/includes/api/class-wc-rest-authentication.php(36): rest_get_url_prefix()
#3 /rachelsquirrel/wp-content/plugins/woocommerce/includes/api/class-wc-rest-authentication.php(55): WC_REST_Authentication->is_request_to_rest_api()
#4 /wordpress/core/4.6.1/wp-includes/plugin.php(235): WC_REST_Authentication->authenticate(false)
#5 /wordpress/core/4.6.1/wp-includes/user.php(2500): apply_filters('determine_curre...', false)
#6 /wordpress/core/4.6.1/wp-includes/pluggable.php(69): _wp_get_current_user()
#7 /wordpress/core/4.6.1/wp-includes/user.php(428): wp_get_current_user()
#8 /rachelsquirrel/wp-content/plugins in /rachelsquirrel/wp-content/plugins/jetpack-pressable-beta/jetpack.php on line 41

The creds for the server are available in the VaultPress MC (#39826).

[jeherve]

Related: #5345

cc @kraftbj

[kraftbj]

I haven't dove too deeply into this, but it looks like the $wp_rewrite global isn't set yet (and will be afk until post-release)? We can probably check to see if $wp_rewrite is an object with a using_index_permalinks method before applying the hotfix?

@rachelsquirrel did you perform any action to generate this error? I'm thinking adding the checks above is good for Jetpack, but wonder if the same thing would happen on 4.7 with the same plugins enabled since Core added using $wp_rewrite there.