Fix #460 transfer qty validation issue

[ariesjia]

fix issue #460

[svk31]

This looks OK, but it doesn't fix the account validation. The issue is that the variable to_account is only updated when a valid account is found, so if you change the input text to a non-valid account name, the old account name is still kept. I suggest you add a toAccountValid variable to the if check you already used here:

const toAccountValid = to_account && to_account.get("name") === this.state.to_name;
if(!from_account || !to_account || !toAccountValid .......

[ariesjia]

@svk31 Thanks for your detail solution , I update toAccount validation code.