Function validate_draw

fn validate_draw(
    vertex: &[Option<VertexState>],
    step: &[VertexStep],
    first_vertex: u32,
    vertex_count: u32,
    first_instance: u32,
    instance_count: u32,
) -> Result<(), DrawError>

https://gpuweb.github.io/gpuweb/#dom-gpurendercommandsmixin-draw