fix: Patch infinite loop by adding a secondary method #177

Collective analysis efforts have found that infinite loop occurs when variables
`beg` and `end` have an identical value in `org-transclusion-remove`.

It's at the top of the function and looks like this:

(beg (marker-position (get-char-property (point)
                                         'org-transclusion-beg-mkr)))
(end (marker-position (get-char-property (point)
                                         'org-transclusion-end-mkr)))

These values are used to know the size of the transclusion to remove it. The
size of overlay on the source cannot be used because filter can alter the text
size. `text-property-search-forward` can be a reliable way to do this.

The message "(org-transclusion) Something is off" is still a WIP version. I
think we need to come up with a better message if the method above is deemed
viable as a preventive measure.

org-transclusion.el

@@ -17,7 +17,7 @@
 
 ;; Author:        Noboru Ota <me@nobiot.com>
 ;; Created:       10 October 2020
-;; Last modified: 20 April 2024
+;; Last modified: 12 May 2024
 
 ;; URL: https://github.com/nobiot/org-transclusion
 ;; Keywords: org-mode, transclusion, writing
@@ -543,6 +543,13 @@ When success, return the beginning point of the keyword re-inserted."
             (keyword (org-transclusion-keyword-plist-to-string keyword-plist))
             (tc-pair-ov (get-char-property (point) 'org-transclusion-pair)))
       (progn
+        (when (equal beg end)
+          (message "(org-transclusion) Something is off")
+          ;; We need to know the size of the transclusion to remove it.
+          ;; The size of overlay cannot be used because filter can change the text.
+          (when-let* ((prop-match (text-property-search-forward 'org-transclusion-beg-mkr)))
+            (setq beg (prop-match-beginning prop-match))
+            (setq end (prop-match-end prop-match))))
         ;; Need to retain the markers of the other adjacent transclusions
         ;; if any.  If their positions differ after insert, move them back
         ;; beg or end