AJAX with WordPress HTTP API - php

Question

I'm new to php and stuck in my tracks here, so any help is appreciated. I've written a few functions in a JS file to render and update a gallery view for a WordPress template I made. From the updateGallery() function, I make an AJAX call after pressing a submit button on the page, but am receiving a "parsererror."
Arguments(3) [{…}, "parsererror", SyntaxError: Unexpected token A in JSON at position 0 at parse (<anonymous>)
at Ut (https://…, callee: ƒ, Symbol(Symbol.iterator): ƒ]
I tried the code for the API request directly in my WP template to render a response and it worked as expected, but when I try to incorporate my script I get the error and I can't figure out what's causing it.
JS
function updateGallery() {
var county = $("#county").val();
jQuery(".galleryGrid").fadeOut("fast", function() {
console.log("ajax request");
jQuery(".galleryGrid").html("").hide();
$.ajax({
type : "GET",
dataType : "JSON",
url : ajax.url,
data : {
action: "get_gallery_data",
county_id : county
},
error: function(response, error) {
console.log(arguments);
alert("Failed because: " + error);
},
success : function(response) {
if(response.type === "success") {
console.log("Success")
renderGrid(response.data);
}
}
});
});
}
PHP
add_action("wp_ajax_nopriv_get_gallery_data", "get_gallery_data");
add_action("wp_ajax_get_gallery_data", "get_gallery_data");
function get_gallery_data() {
$county_id = $_REQUEST[county_id];
$base_api_url = "https://some.api.com/";
$filters = array(
"field" => "field_153",
"operator" =>"is",
"value" => $county_id
);
$filters_url = rawurlencode(json_encode($filters));
$api_url = $base_api_url."?filters=".$filters_url;
$request = wp_remote_get($api_url, array(
"headers" => array(
"Application-Id" => "5xxxxxx",
"REST-API-KEY" => "0xxxxxx",
),
));
$body = wp_remote_retrieve_body($request);
$output = json_decode($body, true);
echo $output;
die();
};

Answer 1

$output = json_decode($body, true);
//Change
$output = json_encode($body, true);