order.order_number liquid object occasionally misfires

[mthdvd]

I've been experiencing some issues with both the {{order.order_number}} and {{order_number}} liquid objects.

I have a script in the "Additional Scripts" section of the order status page. Note that this isn't placed by an app or part of the Shopify Plus scripts. It's a simple script that is manually added by going to Settings > Checkout > Additional Scripts.

The script logs a purchase event each time the status page is loaded and sends a few pieces of information out to a server. Included in the information is the Order Number. It looks something like this:

<script>
track('event', 'purchase', {
'value': {{checkout.total_price | money_without_currency}},
'order_number': {{order.order_number}}
});
</script>

This script has been inconsistent ever since I placed it. Sometimes it works, sometimes it doesn't. I discovered that the {{order.order_number}} value will not populate on occasions, resulting in a script error. I have also tried {{order_number}} with the same inconsistent result. Since this value doesn't seem to be accessible via Javascript through Shopify.checkout I'm at a bit of a loss.

Is there any reason why this value would be unstable? Is there another way I can consistently grab this information?

And just to clarify, I am looking to access the Order Number as it would appear in the orders dashboard in the admin. Not the order ID, order name, or the  {{checkout.order_number}} value.

Thanks in advance for the help!