regex - Marker does not point anywhere from align-regexp (Emacs)

Question

I am having trouble with the marker in calling an align-regexp. Somehow this doesn't work and gives the error "Marker does not point anywhere".

The idea of the function is that it searches for a new paragraph, marks it and then performs the align-regexp on it. Why doesn't it work?

(defun cleanR-align-smallerthan-dash ()
  (interactive)
  (save-excursion
    (goto-char (point-min))
    (while (search-forward-regexp "[
][
]" nil t) ; confirmed to work
      (mark-paragraph)                            ; the error is probably in here
      (align-regexp (region-beginning) (region-end) "<-"))))

Answer 1

The regexp you passed is not what align-regexp is expecting.

See my answer here.