Opps, the awful 16th line (for (let i = 0; i < 100; i++) {) should be replaced with this:
for (let i = 0; i < boardSize * boardSize && 0 < sudokuZeroCellCounter(board, boardSize); i++) {
I did not mean to leave it like that :)
(and sorry about the many variable about dimensions, half of the code if prepared to be used on sudoku boards larger/smaller than 9x9)