UnderlyingCoins balance does not properly use decimals for balance calculation

[0seba]

When calculating the balance of the underlying coins here the decimals are not used (which causes it default to 18 afaik), one example in which this causes problems is in 3CRV metapools, which causes the balance to be $10^{12}$ times less than the real value. Did not find this issue in the exchangeUnderlying handler

Here is the code of the line with the problem

coin.balance = balances ? decimal.fromBigInt(balances![i]) : decimal.ZERO