None of %s are installed

Raise code

            for cmd_variant in cmd_variants:
                cmd_path = shutil.which(cmd_variant)
                if cmd_path:
                    cmd = [cmd_path]
                    break
            else:
                if len(cmd_variants) > 1:
                    raise RuntimeError("None of %s are installed" % ", ".join(cmd_variants))
                else:
                    raise RuntimeError("%s is not installed" % cmd_variants[0])

            defaultoptions = {
                "dvipng": ["-T", "tight", "-z", "9", "--truecolor"],
                "dvisvgm": ["--no-fonts"],
            }