Invalid `colorClassName` in `LoroExtensions` causes `loro-codemirror` to stop functioning silently, without throwing any exception.

[alissa-tung]

question: what does colorClassName refers to?

steps to reproduce:

1. the following code

LoroExtensions(
      this.loroDoc,
      {
        ephemeral: this.ephemeralStore,
        user: {
          name: "Loro",
          colorClassName: "#7B68EE",
        },
      },
      this.undoManager,
    );

steps to fix:

1. colorClassName: "user2",

problematic behavior:

1. loro-codemirror to stop functioning silently, without throwing any exception.
2. initial contents of the underlying LoroDoc does not get rendered in EditorView
3. EditorView does not sync with LoroDoc default sync text
4. subscribeLocalUpdates never fires with edit in EditorView