Transaction

[Error Code: 1101] error caused by: 1 error occurred:
	* transaction execute failed: [Error Code: 1101] cadence runtime error: Execution failed:
  --> 29b24d7eb340a4fa801ef335b89dc6b0bf2897e35bb409246595be130e4ba489:79:20
   |
79 |         let item <- self.listing.purchase(
80 |             payment: <-self.paymentVault
81 |         )
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: pre-condition failed: listing has already been purchased
   --> 4eb8a10cb9f87357.NFTStorefront:271:16
    |
271 |                 self.details.purchased == false: "listing has already been purchased"
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^