improve pagination

cmd/api/handlers-api.go

@@ -403,6 +403,7 @@ func (app *application) VirtualTerminalPaymentSucceeded(w http.ResponseWriter, r
 	_, err = app.SaveTransaction(txn)
 	if err != nil {
 		app.badRequest(w, r, err)
+		return
 	}
 
 	app.writeJSON(w, http.StatusOK, txn)
@@ -602,6 +603,7 @@ func (app *application) GetSale(w http.ResponseWriter, r *http.Request) {
 	order, err := app.DB.GetOrderByID(orderID)
 	if err != nil {
 		app.badRequest(w, r, err)
+		return
 	}
 	app.writeJSON(w, http.StatusOK, order)
 }