insert gives args out of range

[Heime <heimeborgia@protonmail.com>]

I want to display text starting from "(defun" up to the second blank line that is encountered.

But with this code I get 

insert: Args out of range: #<buffer *Defun Sections*>, 2706, 2804

(defun display-text ()
  "Display the text between a line starting with '(defun' and the second blank line."
  (interactive)
  (let ((output-buffer (get-buffer-create "*Defun Sections*")))
    (with-current-buffer output-buffer
      (erase-buffer)) ;; Clear previous contents
    (save-excursion
      (goto-char (point-min))
      (while (re-search-forward "^(defun" nil t)
        (let ((start (match-beginning 0))
              (blank-lines 0)
              end)
          ;; Move forward to find the second blank line
          (while (and (< blank-lines 2)
                      (re-search-forward "^\\s-*$" nil t))
            (setq blank-lines (1+ blank-lines)))
          (setq end (point))
          ;; Ensure the range is valid before inserting
          (when (> end start)
            (with-current-buffer output-buffer
              (insert (buffer-substring-no-properties start end) "\n"))))))
    ;; Display the output buffer
    (display-buffer output-buffer)))