When I click on an internal link to an anchor, I get the error message:
"Wrong type argument: number-or-marker-p"
The same happens if I type C-c C-o on the link. This is mapped to org-open-at-point, which should handle internal links.
However, if I type C-c o on the link, then the cursor goes to the anchor. This is mapped to org-open-at-point-global, which the org info help says is undefined on internal links.
This behavior is new, I believe since the last org package update. I'm currently on org mode version 9.1.2.
------ Example Org File -----------
* headline 1
* headline 2
*** [[Anchor 1]] CLICK ON THIS