fix: guard CCIP-Read dataSlice against short error.data to prevent BUFFER_OVERRUN

[yutonakamura-dev]

Problem

When a CCIP-Read enabled contract reverts with empty or short error.data (e.g. 0x), the OffchainLookup check in #call crashes with BUFFER_OVERRUN instead of propagating the original call error.

This happens because the condition on line 1034 checks error.data for truthiness — "0x" is truthy — then immediately passes it to dataSlice(error.data, 0, 4), which throws when the data is shorter than 4 bytes.

Affects any ENS offchain name lookup (e.g. .xyz domains via CCIP resolvers) where the resolver reverts without data.

Root Cause

// before
if (... && error.data && dataSlice(error.data, 0, 4) === "0x556f1830") {
//          ^^^^^^^^^^
//          "0x" is truthy, but dataSlice("0x", 0, 4) → BUFFER_OVERRUN

Fix

Add a dataLength guard before dataSlice. dataLength is already imported and used elsewhere in the file (line 1711).

// after
if (... && error.data && dataLength(error.data) >= 4 && dataSlice(error.data, 0, 4) === "0x556f1830") {

Reproduction

import { getDefaultProvider, EnsResolver } from 'ethers';

const provider = getDefaultProvider();
const resolver = new EnsResolver(provider, '0xf142b308cf687d4358410a4cb885513b30a42025', 'mnhsu.xyz');
const address = await resolver.getAddress();
// → BUFFER_OVERRUN instead of null

Closes #4982