Fixed: an early Add to cart tap on a subscription-only product usually no longer errors

On a product that's set up to sell only on a subscription plan, Subi's widget needs to attach a selling plan before Shopify will accept an Add to cart request. If a shopper tapped the theme's own Add to cart button before the widget had finished loading, Shopify's cart would reject the request outright, since no plan had been selected yet, so the shopper's tap simply failed.

That early tap is now handled in most theme setups: the storefront picks up the widget's default subscription plan and adds the product with it, or waits for the widget to be ready, instead of sending Shopify a request it has to reject. A shopper who already selected a specific plan, or who taps after the widget has loaded, sees no change in behavior.

This affects only subscription-only products during the brief window before Subi's widget finishes loading on the page. A small number of theme setups, ones whose own Add to cart button does not fire a standard form submit, or that fill in their own empty selling-plan value, are not covered by this fix and can still show the earlier error.