Opening HTML file breaks layout

[DJGummikuh]

Describe the bug
Opening a HTML file in a multi-file module (?) nests all layout into the main panel

This is the License.html File I caused the error with (I was uploading a random zip to check the zip unpacking).
License.html.tar.gz you have to unpack prior to testing, I tar.gz'd it because you cannot upload HTML files here directly :D

To Reproduce
Steps to reproduce the behavior:

1. Go to a model containing a HTML file
2. Click on "Open" for the HTML file.
3. See error

Expected behavior
Either don't attempt to preview HTML files, or prevent nested navigational elements.

Screenshots
See Above

Desktop (please complete the following information):

• OS: Manjaro Linux
• Browser Firefox
• Version 137.0.1

Additional context
-/-

[Floppy]

Manyfoldception!