Allow optional (nil) SKU for order line item

Author: rachelmcr

Networking/Networking/Model/OrderItem.swift

@@ -92,7 +92,7 @@ public struct OrderItem: Codable, Equatable, Hashable, GeneratedFakeable, Genera
         // some plugins alter the field value from String to Int or Decimal.
         let sku = container.failsafeDecodeIfPresent(targetType: String.self,
                                                     forKey: .sku,
-                                                    alternativeTypes: [.decimal(transform: { NSDecimalNumber(decimal: $0).stringValue })]) ?? ""
+                                                    alternativeTypes: [.decimal(transform: { NSDecimalNumber(decimal: $0).stringValue })])
         let subtotal = try container.decode(String.self, forKey: .subtotal)
         let subtotalTax = try container.decode(String.self, forKey: .subtotalTax)
         let taxClass = try container.decode(String.self, forKey: .taxClass)