Transaction

[Error Code: 1101] cadence runtime error Execution failed:
  --> 3cf9f071d0387a46c14b471e0302f227b188f8b671a767d615376e1563637940:80:20
   |
80 |         let item <- self.listing.purchase(
   |                     ^

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