get_balance fails when account doesn't exist

[evgenykuzyakov]

FT/contracts/assemblyscript/nep21-basic/main.ts

Line 102 in 901145f

assert(balanceRegistry.contains(owner_id), ERR_INVALID_ACCOUNT)

Why does the implementation need to fail instead of returning 0?

If you write a contract that checks balance of a user, you now need to handle 2 cases. Does the response failed or returned a value. Instead of always succeed and rerturn.

[idea404]

Examples now in Rust and do return 0 when an account is not registered with the ft_contract