@futurebird
Maybe it could help if you give the explanation you just gave at the beginning of the class - even with a little example of an error they common encounter (e.g. path wrong or typo)? I think the idea that how to understand and solve problems (errors) is what you want to teach is not obvious when people think about coding but also reassuring. And emphasising what works for you (and why) - e.g. ask questions when I make my rounds - could also make students feel more comfortable to say what works for them.

I’ve only ever taught university students, so I wouldn’t know if this works for school age kids. But I have felt flustered myself when attending programming workshops even after a decade of programming semi-regularly - maybe indeed because there is the fear of falling behind during the lessons.