Tutorial issues: wrong default EntryPoint address and incorrect viem destructuring

[Pan-Beibei]

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Tutorial: https://docs.openzeppelin.com/contracts/5.x/learn/webauthn-smart-accounts

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Issue 1: Default entryPoint() doesn't match the tutorial's EntryPoint address

Account.sol defaults to ENTRYPOINT_V09 (0x433709009B8330FDa32311DF1C2AFA402eD8D009), but the tutorial uses ENTRYPOINT_V08 (0x4337084D9E255Ff0702461CF8895CE9E3b5Ff108). This mismatch causes validateUserOp to revert with AA23 because the onlyEntryPoint check fails.

The fix is to add this override to AccountWebAuthn:

function entryPoint() public view virtual override returns (IEntryPoint) {
    return ERC4337Utils.ENTRYPOINT_V08;
}

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Issue 2: predictAddress return value incorrectly destructured

The tutorial uses array destructuring on a function that returns a single address:

// ❌ Wrong - destructures the address string as a char array, predictedAddress = "0"
const [predictedAddress] = await publicClient.readContract({ ... });

// ✅ Correct
const predictedAddress = await publicClient.readContract({ ... });