Edit existing link in HTMLEditor text, does not work if there are too many pages

[baukezwaan]

Module version(s) affected

5.1. and 4.13.

Description

For sites with many childpages under a certain page (for instance newsitems in the Blog-module), it is not possible to see the current link in the tinymce-popup for editing internal links.

This has to do with the node_threshold_leaf preventing the childeren to be loaded in the output of the json of admin/Modals/editorInternalLink/field/PageID/tree.

For the editor this looks like this:

How to reproduce

1. Install default Silverstripe installation
2. In the CMS, create 5 pages under About Us-page.
3. Change title of one of these pages to ABCDEF
4. Edit the homepage Content, and create a hyperlink to page ABCDEF
5. Save the page
6. Observe editing the link, via the TinyMCE interface, shows the currently selected internal page
7. Add a lower threshold in _config.php, by adding this line: SiteTree::config()->set('node_threshold_leaf', 3);
8. Observe editing the link, via the TinyMCE interface, does NOT show the currently selected internal page

In the network panel this is visible, by openig the XHR-request in a new tab:

1. Open https://localhost/admin/Modals/editorInternalLink/field/PageID/tree?forceValue=9&format=json
2. Change the node_threshold_leaf value
3. Refresh the json-page and see the children missing

This is even better visible, when changing the URL to &format=x

When the limit is not reached, this looks something like:

Home
About Us
Home
About Us
  - New Page
  - New Page
  - ABCDEF
  - New Page
Contact Us

But when the threshold is reached:

Home
About Us
  - Too many children (0)
Contact Us

Possible Solution

No response

Additional Context

No response

Validations

• [X] Check that there isn't already an issue that reports the same bug
• [X] Double check that your reproduction steps work in a fresh installation of silverstripe/installer (with any code examples you've provided)