Function render_checked 

pub fn render_checked(
    renderer: &mut dyn Renderer,
    job: &RenderJob,
) -> Result<(Rendered, LoadCheck), LoadFault>

Renders job and checks that the plug-in loaded its preset.

The renderer must not have loaded a state yet: the check renders the init patch twice first, and keeps only the band levels of each clip.

Errors

Returns the LoadFault that explains why the render does not count.