In my wordpress loop, i have added pagination everything is working, except when i navigate to last page.

I have a total of 16 posts and I am displaying 6 posts per page, i can navigate to pages 1 and 2, but when navigate to page 3, that should have contain 4 posts it gives me ‘Page not found’ error.

Can anyone, point out what i am doing wrong, below is my code.

  <div class="posts-container">
    <?php
       $paged = (get_query_var('paged')) ? get_query_var('paged') : 1;
       $args  = array(
            'orderby'        => 'date',
            'posts_per_page' =>  6,
            'paged'          => $paged
       ); 
       $rainbow_posts = new WP_Query($args);
       if($rainbow_posts->have_posts()):
            while($rainbow_posts->have_posts()):
                $rainbow_posts->the_post();
                $post_url = get_permalink();?>
                
                <div class="post">
                    <div class="featured-img">
                        <a href="<?=$post_url;?>">
                            <picture>
                                <img src="<?=get_the_post_thumbnail_url();?>" alt="blog-featured-img" width=387 height=258>
                            </picture>
                        </a>
                    </div>
                    <div class="categories">
                        <span>
                            <?php
                                $categories = get_the_category();
                                foreach ( $categories as $category ) :?>
                                   <a href="<?=esc_url( get_category_link( $category->term_id ) ); ?>"><?=esc_html( $category->name );?></a>
                            <?php
                                   if($category !== end($categories)):?>
                                     |
                                <?php
                                   endif;
                                endforeach;?>
                        </span>
                    </div>
                    <h6><a href="<?=$post_url;?>"><?=esc_html(get_the_title());?></a></h6>
                    <div class="content">
                        <?php
                            $full_content    = get_the_content();
                            $trimmed_content = wp_trim_words( $full_content, 20, '...' );
                            echo $trimmed_content;
                        ?>
                    </div>
                    <div class="avatar">
                        <div class="first-column">
                            <picture>
                                <source media="(max-width:576px)" srcset="<?=get_avatar_url( get_the_author_meta( 'ID' ), array( 'size' => 50 ) );?>" width=50 height=50>
                                <img src="<?=get_avatar_url( get_the_author_meta( 'ID' ), array( 'size' => 100 ) );?>"  width=64 height=62 alt="author">
                            </picture>
                        </div>
                        <div class="second-column">
                            <p><?=get_the_author();?></p>
                            <p><?=get_the_modified_date('d M Y').', '.do_shortcode('[rt_reading_time]').' min read';?></p>
                        </div>
                    </div>
                </div>
       <?php
            endwhile;?>
            <div class="pagination">
                <?=paginate_links(array(
                  'base'         => get_pagenum_link(1) . '%_%',
                  'format'       => 'page/%#%',
                  'current'      => max(1, get_query_var('paged')),
                  'total'        => $rainbow_posts->max_num_pages,
                  'prev_text'    => __('« prev'),
                  'next_text'    => __('next »'),
                ));?>
            </div>
            <?php wp_reset_postdata();
        endif;?>
 </div>

Any help would be greatly appreciated.