Cannot access Object/Array data in PHP function without getting error

Question

I am currently working on a project with PHP, JavaScript and jQuery and have come across an issue. I am trying to get the PHP function getCountryBorders() to return just the polygon information for a country but I cannot seem to access object data with object['property'] as it gives me the

Fatal error: Uncaught TypeError: Cannot access offset of type string on string in C:\xampp\htdocs\worldmap\libs\php\server.php:21 Stack trace: #0 C:\xampp\htdocs\worldmap\libs\php\server.php(10): getCountryBorders('BS') #1 {main} thrown in C:\xampp\htdocs\worldmap\libs\php\server.php on line 21

Any help would be greatly appreciated.

Here is the code:

server.php:

<?php
    if(isset($_POST['action']) && !empty($_POST['action'])) {
        $action = $_POST['action'];
        if(isset($_POST['iso_a2'])) {
            $iso_a2 = $_POST['iso_a2'];
        }

        switch($action) {
            case 'populateSelect' : populateSelect();break;
            case 'getCountryBorders' : getCountryBorders($iso_a2);break;
        };
    };

    function populateSelect() {
        $data = file_get_contents('../../data.json');
        echo $data;
    }

    function getCountryBorders($iso_a2) {
        $data = file_get_contents('../../data.json');
        echo $data['features'];
    }
?>



//index.js
$('#document').ready(() => {
    $.ajax({
        url: 'libs/php/server.php',
        type: 'POST',
        dataType: 'json',
        data: {
            action: 'populateSelect'
        },
        success: (result) => {
            result['features'].forEach((country) => {
                $("<option>", {
                    value: country.properties.iso_a2,
                    text: country.properties.name
                }).appendTo('#countries');
            })
        }
    });
});

$('#countries').change(() => {
    console.log($('#countries').val());
});

$('#test').click(() => {
    alert('Clicked')
    $.ajax({
        url: 'libs/php/server.php',
        type: 'POST',
        dataType: 'json',
        data: {
            action: 'getCountryBorders',
            iso_a2: $('#countries').val()
        },
        success: (result) => {
            console.log(result);
        }
    });
});

The issue is within the $('#test') ajax function.

Thank you,

Liam

I have tried looking at network responses but they just return

Fatal error: Uncaught TypeError: Cannot access offset of type string on string in C:\xampp\htdocs\worldmap\libs\php\server.php:21 Stack trace: #0 C:\xampp\htdocs\worldmap\libs\php\server.php(10): getCountryBorders('BS') #1 {main} thrown in C:\xampp\htdocs\worldmap\libs\php\server.php on line 21