The way to ensure this never happens is to prevent any meaningful FBI probe, which of course they did.
Democrats need to wake up and learn to deal with the GOP by never assuming that they are normal decent people. The words that come out of their mouths need to be parsed as carefully as a contract with a loan shark. No verbal agreements - that only leads to he said she said.
Who knew or thought an FBI investigation could be so constrained as to be meaningless?