Transaction

[Error Code: 1101] cadence runtime error Execution failed:
  --> 85fd8534bcc5e93f1ca5b6f2b4da62a6a02ea0613ea72eee61f9ffc2d3307b95:80:20
   |
80 |         let item <- self.listing.purchase(
   |                     ^

error: pre-condition failed: listing has already been purchased
   --> 4eb8a10cb9f87357.NFTStorefront:243:16