Do not overload index with WithdrawalIndex and ValidatorIndex

[potuz]

in the function withdraw_balance the variable index takes different meanings and types. This confused at least one member of our team.

[ralexstokes]

fwiw the types do not change and I'd say this implies the meaning does not change but I'd support this PR if it clarifies things

[potuz]

fwiw the types do not change and I'd say this implies the meaning does not change but I'd support this PR if it clarifies things

I think the confusing thing is statements like

        index=state.next_withdrawal_index,
        address=ExecutionAddress(state.validators[index].withdrawal_credentials[12:]),

Where in one line index is assigned a WithdrawalIndex and in the very next line, index is used with the ValidatorIndex that was passed to the function.

[hwwhww]

Agreed that index=state.next_withdrawal_index, address=ExecutionAddress(state.validators[index].withdrawal_credentials[12:]) is confusing. 👍

[djrtwo]

makes sense!