[Theme: Perth] Site description/tagline disappears when I add loho

I uploaded a logo onto my company site, and by default it removes the site title and site description (tagline).

I’m using a child theme, and I asked in the aThemes Perth forum how to have my logo AND my site description/tagline show and the moderator gave me this code:

function perth_branding() {
	if ( get_theme_mod('site_logo') ) :
		echo '<a href="' . esc_url( home_url( '/' ) ) . '" title="' . esc_attr(get_bloginfo('name')) . '"><img class="site-logo" src="' . esc_url(get_theme_mod('site_logo')) . '" alt="' . esc_attr(get_bloginfo('name')) . '" /></a>';
		if ( get_bloginfo( 'description' ) ) {
			echo '<h2 class="site-description">' . esc_html(get_bloginfo( 'description' )) . '</h2>';
		}
	else :
		echo '<h1 class="site-title"><a href="' . esc_url( home_url( '/' ) ) . '" rel="home">' . esc_html(get_bloginfo('name')) . '</a></h1>';
		if ( get_bloginfo( 'description' ) ) {
			echo '<h2 class="site-description">' . esc_html(get_bloginfo( 'description' )) . '</h2>';
		}
	endif;
}

This kind of worked, except it brought back the site title, and the description/tagline twice.

I’ve tried modifying the code but keep getting errors.

I just want my logo, and my site description to appear once underneath it.

Any advice?