XF 1.5 CSS Error!

[[xFv]]

Hello!
I am running xf 1.5.5a fresh install locally.
I am trying to set an option for a add-on I am making.
However when I save my template edit, ONLY sidebar.css template throws me this error when I log out, or change to the default style. I dont have this issue any other template. The template edit does work! Any help is much appreciated.

 

[Rasmus Vind]

Whenever I import a template through code using:

$styleModel->importStyleXml($document);

I get the same problem. I can usually fix it by manually re-importing the style.

 

[Paul B]

The error is related to a template referencing a style property which doesn't exist.

That error only appears in debug mode.