In an HTML page, if you have a manually created link in the header, clicking on the edit link will result in a "invalidsection" error, instead of showing the edit page for that section.

Reproduction steps:

1. Create a wiki
2. Create the first page as HTML
3. In your text editor, switch to HTML. Insert the following:

   <h1>This is an example header</h1>

   <p>This is an example paragraph</p>

4. Then switch your text editor back
5. Select one of the words in the header
6. Click the link button and link it to any site (e.g. moodle.org)
7. View the page
8. Click the edit link on the right of the header
9. An error will be displayed