chore: handle unknown events gracefully

Author: stfsy

lib/index.js

@@ -385,9 +385,8 @@ class Subscriptions {
                     })
                     result.amount.total = payment.sale_gross
                     result.amount.method = payment.payment_method
-                } else {
-                    return null
                 }
+
                 return result
             })
     }