Toolbar button when no scene is active

[ben]

It does nothing. Maybe we can detect that situation and disable it?

[rsek]

none of the scene toolbar buttons do anything without an active scene, tho. 🤔 theoretically, they already telegraph their disabled state by rendering with reduced opacity when their parent ul has the disabled class (which should really be an aria attribute, sigh).

which doesn't mean there isn't something to address -- something's causing a mismatch in user expectations. i'd hazard that the root problem is we're putting non-scene-specific functionality (actor creation and the oracle list) in the place where scene-specific controls are supposed to live.