bug: white flash on loading

[joneugster]

When loading with any non-white theme, there is a white flash. In particular this is noticeable in dark mode.

Likely this is caused by the initialisation in lean4monaco (https://github.com/hhu-adam/lean4monaco/blob/main/src/leanmonaco.ts)
and might need to be addressed there.

[joneugster]

As a test, the settings seem to load correctly (getOnInit: true) and are already present on the first render of the editor, so this isn't the issue