In order to “fix” the error, you would need to remove the current menu item and add your own with text.
To do that, you can do this:
remove_filter( 'wp_nav_menu_items', 'generate_menu_search_icon', 10, 2 );
add_filter( 'wp_nav_menu_items', function( $items, $args ) {
if ( isset( $args->theme_location ) && 'primary' === $args->theme_location ) {
return sprintf(
'%1$s<li class="search-item"><a aria-label="%2$s" href="#">%3$s Search</a></li>',
$items,
esc_attr__( 'Open Search Bar', 'generatepress' ),
generate_get_svg_icon( 'search', true )
);
}
return $items;
}, 10, 2 );