Transaction

[Error Code: 1101] cadence runtime error Execution failed:
  --> cd77c6442c7a4e211e99dba8d72de4680a1d8a2f93fdc5bcc3aaea5d3c3ab7b3:80:20
   |
80 |         let item <- self.listing.purchase(
   |                     ^

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