In Jenga, whatever your intentions, you might knock the tower down at any moment. Your actions or a misplacement by the last player might make things so unstable that the tower can only fall.
It’s tempting to think of the viva is a precarious situation, but your thesis is not a Jenga tower, and the viva is not a game.
Questions from examiners aren’t like pulling bricks out. Your answers aren’t going to make your work fall apart. Discussion can bring in some wobbles, but your work is more than a tower of bricks. You designed this structure, it didn’t just come together out of a box.