You seem certain. I have different recollections. And I was so hoping to threaten their demoncrazy.
Under the terms of the 17th Amendment, the governor of the state fills a Senate vacancy. Some states have rules about party affiliation (WA, WY). Some states require the legislature to schedule a special election to fill the vacancy (MA).
House vacancies can only be filled by election. We're late enough in the cycle that the Governor of Texas will not schedule a special election. Her seat will be filled in November's general election.