TypeError in `PageTree.preselect` when clicking on file in files field

[medienbaecker]

Description

When clicking on a file that belongs to a different page in a files field, the Panel throws a JavaScript error (Cannot read properties of undefined (reading '0')) after navigating to this file.

It looks like the error comes from panel/src/components/Navigation/PageTree.vue, line 105 in the preselect method.

Expected behavior
The page loads and displays correctly and the error can be dismissed. I don't understand the full code and what the preselect function is supposed to do here.

To reproduce

1. Create a files field that queries files from a different place (e.g. site.files)
2. Select a file
3. Click on the selected file

Your setup

Kirby Version
5.2.0-rc.1

Console output

TypeError: Cannot read properties of undefined (reading '0')
    at i.preselect (index.min.js:2:287231)

Your system (please complete the following information)

• OS: macOS 26.1
• Browser: Chrome
• Version: 143.0.7499.41

[distantnative]

@medienbaecker youbsre talking about the files field and also about the page tree component. But the files field doesn't use that component. Is this something custom you put together? Or are you actually talking about the link field?

[medienbaecker]

It's a files field. When I click on an already-selected file that belongs to a different page, the Panel opens/navigates to that file. I was honestly just trying to make sense of the error by looking at your source files and assumed this error has something to do with the PageTree component. Could be completely wrong. It was just the only preselect I could find 😅

[distantnative]

I cannot reproduce this. Can you with e.g. a fresh starterkit? Or any fields on the blueprint of that selected file?

[medienbaecker]

It was actually pretty hard to reproduce in a Starterkit, but I did it. Your question about the link field helped me a lot 😅

So the error only happens when you have a link and a files field in a drawer and only after selecting a file in the link field. It has nothing to do with the file being from another page.

The easiest way to reproduce I could find:

1. Create a structure or object field (in order to get a drawer) with both a link and a files field
2. Link to a file in the link field
3. Select any file in the files field
4. Click on the selected file in the files field

CleanShot.2025-12-06.at.12.50.44.mp4

I can also update the initial issue if that helps?

[afbora]

I can reproduce the issue with link and files field combination in structure as well. But this issue introduced with 5.1.0 not just for 5.2.0. I'll track the issue asap.

[afbora]

@distantnative Here the error line:
https://github.com/getkirby/kirby/blob/5.1.0/panel/src/components/Navigation/PageTree.vue#L105

When the link and files fields are used together and the files field is clicked, I think the component is somehow loaded and makes a request to /site/tree:
https://github.com/getkirby/kirby/blob/5.1.0/panel/src/components/Navigation/PageTree.vue#L56

When the drawer is first loaded:

tree.$refs

{"site://": []}

When the files field is clicked:

tree.$refs

{}

[distantnative]

I think it would be good to find out while in the transition to the file view, the drawer/link field is rendered once more (instead of just being unmounted). And ideally fix that.

But I also think the problem starts higher up in the chain: https://github.com/getkirby/kirby/blob/main/panel/src/components/Forms/Field/LinkField.vue#L82 will already feature the file UUID and pass this on to k-file-browser. But k-file-browser only expects a page UUId for opened.