Remove the alt-buffer guard in headless registerMarker so behavior matches the browser terminal. Update headless public API and typings to return IMarker instead of IMarker | undefined. Co-authored-by: Daniel Imms <Tyriar@users.noreply.github.com>
Remove the alt-buffer guard in headless registerMarker so behavior matches the browser terminal. Update headless public API and typings to return IMarker instead of IMarker | undefined. Co-authored-by: Daniel Imms <Tyriar@users.noreply.github.com>