The issue is with calling the 'mintCard' function of the ERC721 contract via the Node.js backend.
The error message indicates that the gas estimate for the transaction is unpredictable, and the function selector was not recognized with no fallback function.
The error occurs when trying to estimate the gas for the transaction, and it suggests that the transaction may fail or require a manual gas limit.
The deployment script and contract artifacts are also mentioned, but they are not directly related to the issue.