Adafruit mlx90640_camtest.py example does a "black screen" in RPi4

The example from adafruit (mlx90640_camtest.py) crashes the RPi4 all the time! This means that when I run the example, the screen goes black and I need to shut down the RPi4. Don't even have time to get the error. The example mlx90640_simpletest.py and also mlx90640_pil.py works good though... any thoughts?

Start by comparing mlx90640_camtest.py with the working mlx90640_simpletest.py and mlx90640_pil.py examples on an RPi4. Reproduce the black-screen crash and capture the error or failing step; done means identifying the cause and documenting or correcting the camtest example so it no longer crashes.

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