Remove conditional tag from header

You need to create a child theme. You can use a plugin to do that, just search for ‘child theme’ on the wordpress plugins search.

After that, you need to copy your header.php to the child theme directory.

Then, you need to change the code above to the following:

  <?php if ( get_bloginfo( 'description' ) || get_bloginfo( 'title' ) ) : 
        // h1 on singular, h2 elsewhere
        $title_type = is_singular() ? '2' : '1'; ?>
        <h<?php echo $title_type; ?> class="blog-title">
            <a href="https://wordpress.stackexchange.com/questions/299196/<?php echo esc_url( home_url() ); ?>" title="<?php echo esc_attr( get_bloginfo( 'title' ) ); ?> &mdash; <?php echo esc_attr( get_bloginfo( 'description' ) ); ?>" rel="home"><?php echo esc_attr( get_bloginfo( 'title' ) ); ?></a>
        </h<?php echo $title_type; ?>>
    <?php endif; ?>

(Just remove the part that checks if an image has been set)

That way, you can update your theme and you won’t loose that change.