Wordpress custom pagination links to a blank page - php

Question

this is my archive of posts: https://polnapol-tarnow.pl/aktualnosci/page/4/
There are only 4 pages but link to another (blank) page is showing up anyway ("Następna strona"). Is there a way to adjust conditions to stop rendering another "Next page" link if there is no another page with posts? I would be very grateful for any help.
Faulty code:
<?php if (!is_paged()) : ?>
<span><?php _e('Next page'); ?> ››</span>
<?php else : ?>
<span><?php _e('Next page'); ?> ››</span>
<?php endif; ?>
Full template:
<?php $b_subitlte = get_field('b_subitlte');
$b_title = get_field('b_title');
$b_desc = get_field('b_desc'); ?>
<section class="blog-home padding czarny">
<?php if ( function_exists('yoast_breadcrumb') ) { ?>
<div class="breadcrumbs">
<div class="container">
<?php yoast_breadcrumb('<p id="breadcrumbs">','</p>'); ?>
</div>
</div>
<?php } ?>
<div class="col-sm-offset-2 col-sm-8 text-center">
<h4 class="upper-title">aktualności</h4>
<h2 class="title">aktywni <br>
nie tylko w kuchni</h2>
<p>nieustannie badamy otaczający świat aby tworzyć nie tylko lepsze potrawy, ale i klimat naszego włoskiego lokalu. Inspirujemy się i piszemy o tym!</p>
</div>
<div class="container">
<div class="row">
<div class="col-sm-offset-2 col-sm-8 text-center">
<h4 class="upper-title"><?php echo $b_subitlte; ?></h4>
<h2 class="title black"><?php echo $b_title; ?></h2>
<p><?php echo $b_desc; ?></p>
</div>
</div>
<?php
$args = array(
'posts_per_page' => 5,
'paged' => (get_query_var('paged')) ? get_query_var('paged') : 1
);
$news = new WP_Query( $args );
if ( $news->have_posts() ) : ?>
<div class="blog-wrapper row">
<?php while ( $news->have_posts() ) : $news->the_post(); ?>
<?php $blog_short = get_field('blog_short'); ?>
<div class="col-md-4 col-xs-6">
<?php if ( has_post_thumbnail() ) : ?>
<?php $url = wp_get_attachment_url( get_post_thumbnail_id($post->ID) ); ?>
<div style="background-image: url(<?php echo $url; ?>)" class="thumbnail-cover">
<?php the_post_thumbnail($post->ID);?>
<a href="<?php the_permalink(); ?>" title="<?php the_title_attribute(); ?>" class="custom-hover">
<span class="main-btn">zobacz post</span>
</a>
</div>
<?php endif; ?>
<p class="meta"><?php the_time('Y-m-d'); ?></p>
<h2 class="title">
<?php the_title(); ?>
</h2>
<p><?php echo $blog_short; ?></p>
</div>
<?php endwhile; ?>
</div>
<?php echo previous_posts_link(); ?>
<?php if (!is_paged()) : ?>
<span><?php _e('Nastepna strona'); ?> ››</span>
<?php else : ?>
<span><?php _e('Następna strona'); ?> ››</span>
<?php endif; ?>
<?php endif; wp_reset_postdata(); ?>
</div>
</section>
</div>

Answer 1

You should use the pagination of WordPress. Go to this link: WordPress pagination
You can use this template for your pagination :
<div class="paginate">
<?php
global $wp_query;
$big = 999999999; // need an unlikely integer
echo paginate_links( array(
'base' => str_replace( $big, '%#%', esc_url( get_pagenum_link( $big ) ) ),
'format' => '?paged=%#%',
'current' => max( 1, get_query_var('paged') ),
'total' => $wp_query->max_num_pages,
'prev_text' => '<<' ,
'next_text' => '>>' ,
) );
?>
</div>
And you can set a number of the post in one page by going WordPress panel > setting > reading > blog page show at most.

Answer 2

I managed to fix this issue by counting all published posts and dividing them by number of posts per page (in this case 5 posts):
$count_posts = wp_count_posts()-> publish / 5;
So my code was:
<?php echo previous_posts_link(); ?>
<?php if (!is_paged()):?>
<span><?php _e('Previous page'); ?> ››</span>
<?php elseif ($count_posts > $paged ):?>
<span><?php _e('Next page'); ?> ››</span>
<?php else : ?>
<?php endif; ?>