When a handle is minted, its tokenId is computed as the keccak256 hash of the handle name:
LensHandles.sol#L182-L184
However, _mintHandle() does not ensure that the tokenId minted is not 0:
LensHandles.sol#L194-L200
This makes it theoretically possible to mint a handle with a tokenId of 0, which is problematic as tokenId == 0 is treated as a default value in the protocol. For example, getDefaultHandle() in TokenHandleRegistry returns profile ID as 0 when the handle tokenId is 0:
TokenHandleRegistry.sol#L100-L102
In _mintHandle(), consider checking that tokenId is non-zero to protect against the extremely unlikely event where a localName results in tokenId = 0:
LensHandles.sol#L194-L200
