Add Event Listener to RevenueCatUI.presentPaywall - Capacitor

Hey ​@max-c4cd33 ,

RevenueCatUI only provides paywallDisplayed and paywallDismissed event listeners, but you can handle restore purchases and purchase errors by combining the PaywallResult from RevenueCatUI with the Purchases SDK's customer info listener:

• restorePurchases with no active subscriptions: check the PaywallResult returned from presentPaywall() (example here) - when it's RESTORED, you can then inspect the CustomerInfo to see if there are active entitlements.
   
• Purchase/Restore Errors: when PaywallResult is ERROR, this indicates an error occurred during the transaction, but specific error details are not included in the result. You can use verbose logging and check CustomerInfo updates to understand what happened.
   
• CustomerInfo Updates: use addCustomerInfoUpdateListener() (docs here)from the main Purchases SDK (not RevenueCatUI) to listen for any customer info changes, which fires after restores, purchases, and other subscription events.

 For more information on displaying paywalls, see the official documentation.

Quick Example Snippet:

import { Purchases, LOG_LEVEL } from '@revenuecat/purchases-capacitor';
import { RevenueCatUI, PAYWALL_RESULT } from '@revenuecat/purchases-capacitor-ui';

// Enable verbose logging for debugging (optional)
await Purchases.setLogLevel({ level: LOG_LEVEL.VERBOSE });

// Set up listener during app initialization
await Purchases.addCustomerInfoUpdateListener((customerInfo) => {
  const hasActiveEntitlements = Object.keys(customerInfo.entitlements.active).length > 0;

  if (!hasActiveEntitlements) {
    console.log('DEBUG: No active subscriptions found');
  }
});

// When presenting paywall
try {
  const paywallResult = await RevenueCatUI.presentPaywall();

  switch (paywallResult.result) {
    case PAYWALL_RESULT.RESTORED:
      // Restore completed - check customer info
      const { customerInfo } = await Purchases.getCustomerInfo();
      const hasActive = Object.keys(customerInfo.entitlements.active).length > 0;
      if (!hasActive) {
        console.log('DEBUG: Restored purchases successfully with no subscriptions');
      }
      break;

    case PAYWALL_RESULT.ERROR:
      // An error occurred during purchase or restore
      // Specific error details are not available in the result
      // Check logs and CustomerInfo for more information
      console.error('Transaction error occurred');
      break;

    case PAYWALL_RESULT.PURCHASED:
      console.log('Purchase successful');
      break;

    case PAYWALL_RESULT.CANCELLED:
      console.log('Paywall dismissed without action');
      break;
  }

} catch (error) {
  // Handle paywall presentation errors
  console.error('Paywall presentation error:', error);
}

This should help you in monitoring those other cases you mentioned.