Disable capturing on Pending Payment Orders

[mattallan]

While testing some less common cases for #44 I got the following fatal error when trying to capture a pending payment made through PayPal Checkout:

30-Sep-2020 03:25:46 UTC] PHP Fatal error:  Uncaught Error: Call to a member function authorizations() on null in /Users/matt/local/store/wp-content/plugins/paypal-for-woocommerce/modules/ppcp-wc-gateway/src/Processor/class-authorizedpaymentsprocessor.php:136
Stack trace:
#0 /Users/matt/local/store/wp-content/plugins/paypal-for-woocommerce/modules/ppcp-wc-gateway/src/Processor/class-authorizedpaymentsprocessor.php(86): WooCommerce\PayPalCommerce\WcGateway\Processor\AuthorizedPaymentsProcessor->all_authorizations(Object(WooCommerce\PayPalCommerce\ApiClient\Entity\Order))
#1 /Users/matt/local/store/wp-content/plugins/paypal-for-woocommerce/modules/ppcp-wc-gateway/src/Gateway/class-paypalgateway.php(200): WooCommerce\PayPalCommerce\WcGateway\Processor\AuthorizedPaymentsProcessor->process(Object(Automattic\WooCommerce\Admin\Overrides\Order))
#2 /Users/matt/local/store/wp-content/plugins/paypal-for-woocommerce/modules/ppcp-wc-gateway/src/class-wcgatewaymodule.php(278): WooCommerce\PayPalCommerce\WcGateway\Gateway\PayPalGateway->capture_authorized_payment(Ob in /Users/matt/local/store/wp-content/plugins/paypal-for-woocommerce/modules/ppcp-wc-gateway/src/Processor/class-authorizedpaymentsprocessor.php on line 136

Steps to reproduce

1. Set intent to Authorize in: WooCommerce > Settings > Payments > PayPal
2. Add a product to the cart
3. Visit the checkout and click on the PayPal button
4. Once PayPal pop-up appears you can close it
5. Visit the new Pending Payment order Edit Order page
6. Try to capture the payment and you'll get the above fatal error

Expected Behaviour

Can we hide the capture action on orders that haven't been paid for?