OK, I did just now reach some form of “breakthrough”. I got a clue from your replies (many thanks for that!) and figured out that splitting the test set with 30 was impossible cause it was too small. So I changed its size. The code runs now, the output plot is just not right yet.
That said… Feel welcome to check anyways. I’ll PM it.
EDIT: Nope, can’t find how to if I even can PM. See next post instead.