I have booted with a live Leap USB stick, and it shows exactly the same errors,
all 3 of them, but then it boots just fine. So I guess I was right here:
> (though I think I was seeing at least the last two also when I could boot)
Therefore those error must be completely unrelated.
That's funny because the way I found out about nomodeset as a workaround to be
able to boot, was by googling the errors.