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.
I’m more than certain.
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Don’t sweat it. People live and some times learn.
But not always.