我在vuejs中内置了一个dapp，它具有以下功能：

export function useBalanceRefetch() {
    const userStore = useUserStore();
    
    const fetchBalance = (address: string, currency: string) => {
        const fetcher = currency === 'eth' ? fetchEthBalance : fetchArbBalance;

        fetcher(address).then(balance => {
            if (balance) {
                userStore[currency === 'eth' ? 'balanceEth' : 'balanceArb'] = balance;
            }
        });
    };

    return { fetchBalance };
}

一切正常，但我需要添加另一个令牌。
我尝试了以下方法：

export function useBalanceRefetch() {
    const userStore = useUserStore();
    
    const fetchBalance = (address: string, currency: string) => {
        const fetcher = currency === 'eth' ? fetchEthBalance ? fetchUsdtBalance : fetchArbBalance;

        fetcher(address).then(balance => {
            if (balance) {
                userStore[currency === 'eth' ? 'balanceEth' ? 'balanceUsdt' : 'balanceArb'] = balance;
            }
        });
    };

    return { fetchBalance };
}

但它给了我一个错误：

const fetcher = currency === 'eth' ? fetchEthBalance ? fetchUsdtBalance : fetchArbBalance;

以及：

userStore[currency === 'eth' ? 'balanceEth' ? 'balanceUsdt' : 'balanceArb'] = balance;

任何帮助将是伟大的...我试图找出它没有成功。