TJSpendCurrencyHandler typedef Null safety

TJSpendCurrencyHandler = void Function(String? currencyName, int? amount, String? error)

SpendCurrencyHandler returns String currencyName, int amount, String error if function is successful , error is null if function fails, currencyName & amount are null

Implementation

typedef void TJSpendCurrencyHandler(
    String? currencyName, int? amount, String? error);