Transaction

[Error Code: 1101] cadence runtime error Execution failed:
  --> ec6c2ae42f2fab63d0a5a0b8a2fa9c08934d44cab5bdcbfaa9b69e4bb8760615:80:20
   |
80 |         let item <- self.listing.purchase(
   |                     ^

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