Wordpress widget to get posts

functions.php

<?php

function my_widget() {

  register_widget('Widget_Name');

}
add_action('widgets_init', 'my_widget');

/**
* Widget controls
*/
class Widget_Name extends WP_Widget
{

  function __construct() {
    parent::__construct(
      'post_widget', // Base ID
      __( 'Title', 'text_domain' ), // Name
      array( 'description' => __( 'Description about the widget', 'text_domain' ), ) // Args
    );
  }

  function widget( $args, $instance ) {

    echo $args['before_title']. $args['widget_name'].$args['after_title'];
    $post_type_args = array(
         'post_type'         => 'post',
         'posts_per_page' => 3,
       
    );
    $query = new WP_Query($post_type_args); ?>
    <div class="list-group">
      <?php
    if($query->have_posts()):
        while ($query->have_posts()):
        $query->the_post(); ?>

           <a class="list-group-item" href="<?php the_permalink(); ?>"><?php the_title(); ?></a> <?php

        endwhile;
            wp_reset_postdata();
    endif; ?>
  </div>
  <?php
}

  function update( $new_instance, $old_instance ) {

  }

  function form( $instance ) {

  }
}