Snowman Merkle Airdrop

Description:

The SnowmanAirdrop contract contains a critical typo in the MESSAGE_TYPEHASH constant. The type signature incorrectly specifies "addres" instead of "address" in the string "SnowmanClaim(addres receiver, uint256 amount)". This malformed typehash breaks the EIP-712 signature verification mechanism, rendering the entire airdrop contract non-functional.

EIP-712 requires exact string matching for type signatures when computing domain separators and message hashes. The incorrect typehash generates a completely different hash value than what client-side applications would produce when creating signatures with the correct "address" type, causing all signature validation attempts to fail.

Attack path:

1. User attempts to claim Snowman NFT by calling claimSnowman() with valid Merkle proof and signature

2. Contract calls getMessageHash() which uses the malformed MESSAGE_TYPEHASH containing "addres"

3. The computed message hash differs from the hash used to generate the user's signature (which correctly uses "address")

4. _isValidSignature() fails to recover the correct signer address from the signature

5. Transaction reverts with SA__InvalidSignature() error

6. No legitimate user can successfully claim their airdrop, regardless of having valid proofs and signatures

Impact:

The entire airdrop mechanism is non-functional

Recommended Mitigation:

Fix the typo in SnowmanAirdrop.sol: