ENGCOM-3191: Braintree Paypal Review: check if variable is array when validating request data #18614

 - Merge Pull Request #18614 from deninchoo/magento2:2.3-develop
 - Merged commits:
   1. 44e89c7
   2. 43cb064
   3. 06237d6

Author: magento-engcom-team

app/code/Magento/Braintree/Controller/Paypal/Review.php

@@ -60,7 +60,7 @@ public function execute()
         try {
             $this->validateQuote($quote);
 
-            if ($this->validateRequestData($requestData)) {
+            if ($requestData && $this->validateRequestData($requestData)) {
                 $this->quoteUpdater->execute(
                     $requestData['nonce'],
                     $requestData['details'],