Why does my free app creation with Laravel template yield a pricing error?

Shopify Discussion
1

I am using PHP(Laravel) template for creating APP. I want app to be free and configured following in the config file shopify.php.

"billing" => [
        "required" => true,

        // Example set of values to create a charge for $5 one time
        "chargeName" => "Free",
        "amount" => 0,
        "currencyCode" => "USD", // Currently only supports USD
        "interval" => EnsureBilling::INTERVAL_ANNUAL,
    ]

But after app installation it is giving following error.
Price must be greater than zero

Array
(
    [confirmationUrl] => 
    [userErrors] => Array
        (
            [0] => Array
                (
                    [field] => 
                    [message] => Validation failed: Price must be greater than zero
                )

        )

)

I tried with other intervals and searched solution on other places but got no success.