If owners balance after the transfer is 0 the contract mints amount 0.

[radicleart]

There is a bug in the SFT minting contract which makes it possible for an address to own zero quantity of a given SFT. This in turn makes it look like the address owns some SFT when calling the API methods and also causes problems with post conditions when calling transfer transactions.

The code responsible;

                 (try! (tag-nft-token-id {token-id: token-id, owner: sender}))
		(try! (tag-nft-token-id {token-id: token-id, owner: recipient}))

should read;

		(if (< amount sender-balance) 
			(try! (tag-nft-token-id {token-id: token-id, owner: sender}))
			(try! (nft-burn? artwork-token {token-id: token-id, owner: sender} sender))
		)
		(try! (tag-nft-token-id {token-id: token-id, owner: recipient}))

Ie avoid minting back to owner if balance is going to 0.