MalformedResponse: the first element must be a 'simple_response', a 'structured_response' or a 'custom_response'

[bit111]

Hello,
I tried to use this lib to simply print a BasicCard response but I have the following error:
_MalformedResponse final_response.rich_response: the first element must be a 'simple_response', a 'structured_response' or a 'custom_response'. _

And this is the code I used:

<?php

require './vendor/autoload.php';

use Dialogflow\WebhookClient;

use Dialogflow\Action\Responses\SimpleResponse;
use Dialogflow\Action\Responses\BasicCard;
/*
use Dialogflow\Action\Responses\Image;

use Dialogflow\Action\Questions\Carousel;
use Dialogflow\Action\Questions\Carousel\Option;

use \Dialogflow\RichMessage\Image;
*/


$agent = new WebhookClient(json_decode(file_get_contents('php://input'),true));

if ('question_intercept'==$agent->getIntent()) 
{
	$conv = $agent->getActionConversation();

	$question = $agent->getParameters()['questionValue'];
	if ($question == "picture")
	{
		$conv->close(BasicCard::create()
		    ->title('This is a title')
		    ->formattedText('This is a subtitle')
		    ->image('https://picsum.photos/400/300')
		    ->button('This is a button', 'https://docs.dialogflow.com/')
		);
				
		$agent->reply( $conv );
	}
	else
	{
		$agent->reply('You said: ' . $question);
	}
}
else
{
	$agent->reply('Failed');
}

header('Content-type: application/json');
echo json_encode($agent->render());

?>

[basiteaal]

@bit111 Probably related to the fact that you should also set a 'simple' response next to a rich message.
You are not looking after the device an end-user uses while working with the assistant. BasicCards are more into Google Actions rather than let's say Facebook Messenger etc.

My best guess is to use a simple response next to the basic card and it should work.