“wrong attachement” error with opening popup from Media Library

When opening the “Crop image” popup from images in the Media Library (so, not from out of editing a post), the following error is being showed:

{"status":"error","message":"wrong attachement"}

Following the code it is from these lines:

$src_file_url = wp_get_attachment_image_src($postId, 'full');
if (!$src_file_url) {
	echo json_encode (array('status' => 'error', 'message' => 'wrong attachement' ) );
	exit;
}

This only happens when opening from the Media Library itself. When opening the Media Library from a “edit post” page, it just works fine.