update to matrix class, stopping early

[aditi-goyal-523]

Hi all! I'm trying to run eagle, and I'm running into some version issues with R. There is a

stopifnot(all(sapply(xFull, class) == "matrix"), all(sapply(xNull, class) == "matrix"))

line in the code, but as of R 4.3, matrices now show up as "matrix" "array" when indicating their class. Is there a way to update the stop check so we can run the tutorial? Thanks!