PHP Notice spamming debug.log

Hi @neyl8

Thank you for using our plugin!

We could of course add a check to see if $_SERVER['REQUEST_METHOD'] is set to prevent these notice, but if you are getting these notices from our plugin, you should also be getting them from WordPress core. The code you are getting the notices from is triggered by the WordPress filter rest_pre_serve_request (see: https://github.com/WordPress/WordPress/blob/master/wp-includes/rest-api/class-wp-rest-server.php#L465) Now if you look at that class from WordPress core, you can see that before invoking that filter they also use the REQUEST_METHOD (See: https://github.com/WordPress/WordPress/blob/master/wp-includes/rest-api/class-wp-rest-server.php#L392).
So it seems your server is doing something wrong which causes REQUEST_METHOD to not being set. Now adding a check to our code to prevent the notice would indeed prevent the notice, but the absence of REQUEST_METHOD would still cause issues in the working of our plugin, since we do a check to see if the current request is a GET-request.