net::ERR_EMPTY_RESPONSE

Trying desperately to make a basic call to the V2 API. Both jQuery and Angular give me this error:

GET http://127.0.0.1:8888/recruitler/wp-json/wp/v2/posts/1 net::ERR_EMPTY_RESPONSE

when making a basic GET. I thought It may be some 3rd party software on my work Mac but I brought it to my PC and still the error persists.

I’ll post the jQuery call for simplicity:

jQuery.get( 'http://127.0.0.1:8888/recruitler/wp-json/wp/v2/posts/1', function( data ) {
	$( ".result" ).html( data );
	alert( "Load was performed." );
});

Can someone help me understand what’s going on? This is built from what I’ve read in the documentation. I must be missing something crucial.
https://wordpress.org/plugins/rest-api/