fix create purchase order for 1688 processor

app/Classes/Modules/Bookings/Processors/CreatePurchaseOrderFor1688OrderProcessor.php

@@ -54,6 +54,7 @@ class CreatePurchaseOrderFor1688OrderProcessor
         $billNumber = $this->generatesTransactionBillNumber->execute('PO-');
 
         $documents = $booking->documents()->where('document_type', DocumentType::ECOMMERCE_PURCHASE_ORDER)->get();
+        $products = [];
         foreach($documents as $document) {
             foreach ($document->files as $file) {
                 try {
@@ -64,6 +65,8 @@ class CreatePurchaseOrderFor1688OrderProcessor
             }
         }
 
+        if(empty($products)) return false;
+
         $total = collect($products)->sum(function($product){
             return $product['quantity'] * floatval(str_replace(',', '', $product['unit_price']));
         });