Transaction

[Error Code: 1101] cadence runtime error Execution failed:
  --> bcf969c2e7d1b6d86b9523cdceaa8e568bfe1e42fb9b4c9ea8e2bdd1a535cde7:80:20
   |
80 |         let item <- self.listing.purchase(
   |                     ^

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