Transaction

[Error Code: 1101] cadence runtime error Execution failed:
  --> 6f3cb89a5f7790ef8d1bb7c4f0ac57d8952e5e963c9af88f8cec60f4f3947ada:80:20
   |
80 |         let item <- self.listing.purchase(
   |                     ^

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