Javascript Unexpected token { in JSON with Twig variable

I'm trying to create a gallery just using Twig and Javascript. First of all, I have a functions that returnsa JSON object of the database values of the images.

In event.php file, I do the following:

$gallery_img = $bdclass->getImages() // JSON_encode

echo $twig->render('event.html', ['gallery' => $gallery_img]);

In event.html I import the following Javascript file:

var json_img = '{{ gallery }}' // Twig's variable containing JSON
const IMG = JSON.parse(json_img) // Line 2
var current = 0

function previous() {
    if(current <= 0) {
        current = IMG.length - 1
    }

    else {
        current--
    }

    document.getElementById("event-img").src = IMG[current]
}

function next() {
    current = (current + 1) % IMG.length
    document.getElementById("event-img").src = IMG[current]
}

I'm getting the following error in the console:

Unexpected token { in JSON at position 1 at JSON.parse () at gallery.js:2

I've checked using echo() that the object is returned as a JSON object server-ide (in event.php), but I can't get Twig and Javascript to work. Any help is appreciated.