Steps to reproduce

Install a fresh version of LimeSurvey.

Login to the LimeSurvey administration panel.

Go to Configuration > Themes.

Select a theme, for example "Fruity".

Open the Theme Editor.

In the preview section of welcome screen, I can see the theme preview, but at the top of the preview I also see the following message:

"Caution: JavaScript execution is disabled in your browser or for this website. You may not be able to answer all questions in this survey. Please, verify your browser parameters."

Expected result

When opening the Theme Editor for a theme (e.g., Fruity), the Welcome page preview should appear correctly, fully styled according to the theme.
There should be no errors or warnings, and the layout, text, and design should reflect the selected theme without any visual or functional issues.

Actual result

After opening the Theme Editor and loading the preview of the Welcome page, the preview displays with the following issues:

At the top of the preview, the following warning message appears:

"Caution: JavaScript execution is disabled in your browser or for this website. You may not be able to answer all questions in this survey. Please, verify your browser parameters."

This message is incorrect, because JavaScript is fully enabled in the browser.

The Welcome page preview itself has graphical issues, including:

Some elements appear misaligned.
Certain styles are not applied correctly.
The overall appearance does not match the expected look of the selected theme.
The browser console reports several JavaScript errors, including:

Uncaught ReferenceError: LSvar is not defined
Uncaught TypeError: Cannot read properties of undefined (reading 'hideQuestionWithRelevanceSubQuestion')
Uncaught ReferenceError: activateLanguageChanger is not defined
Uncaught TypeError: Cannot read properties of undefined (reading 'init')