If a theme is updated to introduce a new setting AND immediately make use of it in a stylesheet, then an error was being shown. This is because the stylesheet compilation was using the theme's cached settings, and the cache is only cleared **after** the theme has finished compiling.
This commit updates the SCSS compilation to use uncached values for settings. A similar fix was applied to other parts of theme compilation back in 2020: (a51b8d9c66)