Make sure product exists before using it in ajax response

[nbloomf]

The WC_Stripe_Payment_Request::ajax_add_to_cart() function takes a product ID from the request body and passes it to wc_get_product(). That function will return null if the product is not found, and false if the function call happened out of order (that is, before some prerequisite hooks have run).

Currently we're assuming that the product lookup succeeded, but if it doesn't then the $product->get_type() call on the following line raises a critical error like Uncaught Error: Call to a member function get_type() on bool.

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• Added changelog entry in both changelog.txt and readme.txt (or does not apply)
• Tested on mobile (or does not apply)

Post merge

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[annemirasol]

Hey @nbloomf, thanks for taking care of this!

We're actually phasing out Payment Request buttons in the next release (scheduled in a few days), so this path will soon be unused.

Could you put this check in the new path here, please? Thanks!

woocommerce-gateway-stripe/includes/payment-methods/class-wc-stripe-express-checkout-ajax-handler.php

Line 77 in 0a93ce6

public function ajax_add_to_cart() {