JSON error with a shortcode on a page

Hi,
I created a snippet to create a shortcode. This code also works in a hook attached to the WP profile display. When I use this short code on a page I get an invalid JSON return error when I save the page. However the page is saved and the shortcode works. What do you think of that ? how to resolve this error ? This is the snippet :

add_shortcode( 'carte_sur_page', function () {
	$membership_id=1;
	$wp_id=get_current_user_id();
	$member = eme_get_members_by_wpid_membershipid($wp_id, $membership_id);
	if (!empty($member)) {
		$member=$member[0];
		$answers=eme_get_member_answers($member['member_id']);
		$coupon=$answers[0];
		$conso=$answers[1];
	?>
	<h3>Vous avez déjà une carte de réduction</h3>
	<li>Nombre de coupons disponibles : <?php echo $coupon['answer'] ?></li>
	<li> Dates des navigations payées par carte : <?php echo $conso['answer'] ?></li>
	<?php } });