Function resolveChainId

Resolve a chain name or numeric chainid to a numeric chainid.

• null / undefined / '' defaults to Ethereum mainnet (1).
• A number, an all-digit string, or a 0x hex string (the EIP-155 form that eth_chainId returns) is passed through once validated as a positive integer.
• Surrounding whitespace in a string is ignored (values from env/config files).
• A known name is mapped to its chainid.
• A retired or unknown name throws — silently switching networks on a blockchain client is dangerous (wrong-chain reads look successful).