Price fix

engine/fetdata/shop_product.go

@@ -134,11 +134,7 @@ func (this *ShopProduct) Price() float64 {
 	if this == nil {
 		return 0
 	}
-	if this.currency == nil {
-		return this.object.A_price
-	} else {
-		return this.object.A_price * this.currency.Coefficient()
-	}
+	return this.object.A_price * this.Currency().Coefficient()
 }
 
 func (this *ShopProduct) PriceFormat(format string) string {