pub fn validate_scene(expr: &Expr) -> Result<(), SceneError>Expand description
Validate that expr is a well-formed scene, failing closed with a
SceneError otherwise.
The root must be a scene node (a map tagged with a recognized scene/<kind>
symbol). Nested maps that carry a kind key are validated as scene nodes
too; maps without a kind key are treated as plain data and only recursed
into. This keeps the metadata open (arbitrary data may ride along) while
still rejecting a map that claims to be a scene node but is not one.