The tokenURI() function in NonfungibleTokenPositionDescriptor contract does not explicitly validate token existence before generating and returning metadata, which violates EIP-721 standard requirements.
The NonfungibleTokenPositionDescriptor contract implements a tokenURI() function that generates metadata for NFT positions. However, it fails to explicitly verify if the queried token exists before attempting to retrieve its position data and generate the URI. While the function does call positionManager.positions(tokenId) which may revert for invalid tokens, the EIP-721 standard specifically requires that tokenURI() must verify token existence and revert for invalid tokens. Relying on implicit validation through the positions call does not provide the clear validation required by the standard.
NonfungibleTokenPositionDescriptor.sol#L46-L86:
Add an explicit token existence check using the IERC721 ownerOf() function before processing the token metadata.
While the current implementation may work in practice through implicit validation, the lack of explicit token existence checking represents a deviation from EIP-721 standards that should be addressed through proper validation using ownerOf().
