Combatting nerves and anxieties ahead of the viva is like cutting the heads off the hydra of myth: cleave away the head of concern about typos, and it’s replace with two heads of slightly-unclear passages. Become certain that your examiners are good choices, and you can then stress about what each of them might think.
Every attempt to squash away nerves or thwart little anxieties will make you more and more open to spotting things that could make you nervous. It’s fine to practically assess and fix issues, but doing so to try and push nerves away is not a great strategy.
Unlike ancient heroes though, you have a choice: you don’t have to fight this hydra at all. You have to prepare, but your goal does not have to be eliminating nerves – more will always pop up – instead you can work to build your confidence.
Turn away from the worry-hydra. Work to become more certain of your ability. Worries are not the real challenge in the viva. Greater confidence in yourself and in your work can help you to respond to challenges in the viva, and also put pre-viva worries in perspective.