Creating a custom category widget in wordpress

I am trying to create a custom category widget to show taxonomy package-category from wordpress’s default category widget.

I make changes in $cat_args in custom category widget to show the package-categories.

The problem is that this change is affecting the default wp category widget.

Please guide me where I am wrong?

<?php
class Custom_Widget_Categories extends WP_Widget {

public function __construct() {
    $widget_ops = array( 'classname' => 'widget_categories', 'description' => __( "A list or dropdown of categories." ) );
    parent::__construct('categories', __('Ank Categories'), $widget_ops);
}

public function widget( $args, $instance ) {

    /** This filter is documented in wp-includes/default-widgets.php */
    $title = apply_filters( 'widget_title', empty( $instance['title'] ) ? __( 'Categories' ) : $instance['title'], $instance, $this->id_base );

    $c = ! empty( $instance['count'] ) ? '1' : '0';
    $h = ! empty( $instance['hierarchical'] ) ? '1' : '0';
    $d = ! empty( $instance['dropdown'] ) ? '1' : '0';

    echo $args['before_widget'];
    if ( $title ) {
        echo $args['before_title'] . $title . $args['after_title'];
    }

    $cat_args = array(
        'orderby'      => 'name',
        'show_count'   => $c,
        'hierarchical' => $h,
        'taxonomy'           => 'package-category'
    );

    if ( $d ) {
        static $first_dropdown = true;

        $dropdown_id = ( $first_dropdown ) ? 'cat' : "{$this->id_base}-dropdown-{$this->number}";
        $first_dropdown = false;

        echo '<label class="screen-reader-text" for="' . esc_attr( $dropdown_id ) . '">' . $title . '</label>';

        $cat_args['show_option_none'] = __( 'Select Category' );
        $cat_args['id'] = $dropdown_id;

        /**
         * Filter the arguments for the Categories widget drop-down.
         *
         * @since 2.8.0
         *
         * @see wp_dropdown_categories()
         *
         * @param array $cat_args An array of Categories widget drop-down arguments.
         */
        wp_dropdown_categories( $cat_args );
        ?>

        <script type='text/javascript'>
            /* <![CDATA[ */
            (function() {
                var dropdown = document.getElementById( "<?php echo esc_js( $dropdown_id ); ?>" );
                function onCatChange() {
                    if ( dropdown.options[ dropdown.selectedIndex ].value > 0 ) {
                        location.href = "<?php echo home_url(); ?>/?cat=" + dropdown.options[ dropdown.selectedIndex ].value;
                    }
                }
                dropdown.onchange = onCatChange;
            })();
            /* ]]> */
        </script>

    <?php
    } else {
        ?>
        <ul>
            <?php
            $cat_args['title_li'] = '';

            /**
             * Filter the arguments for the Categories widget.
             *
             * @since 2.8.0
             *
             * @param array $cat_args An array of Categories widget options.
             */
            wp_list_categories( $cat_args );
            ?>
        </ul>
    <?php
    }

    echo $args['after_widget'];
}

public function update( $new_instance, $old_instance ) {
    $instance = $old_instance;
    $instance['title'] = strip_tags($new_instance['title']);
    $instance['count'] = !empty($new_instance['count']) ? 1 : 0;
    $instance['hierarchical'] = !empty($new_instance['hierarchical']) ? 1 : 0;
    $instance['dropdown'] = !empty($new_instance['dropdown']) ? 1 : 0;

    return $instance;
}

public function form( $instance ) {
    //Defaults
    $instance = wp_parse_args( (array) $instance, array( 'title' => '') );
    $title = esc_attr( $instance['title'] );
    $count = isset($instance['count']) ? (bool) $instance['count'] :false;
    $hierarchical = isset( $instance['hierarchical'] ) ? (bool) $instance['hierarchical'] : false;
    $dropdown = isset( $instance['dropdown'] ) ? (bool) $instance['dropdown'] : false;
    ?>
    <p><label for="<?php echo $this->get_field_id('title'); ?>"><?php _e( 'Title:' ); ?></label>
        <input class="widefat" id="<?php echo $this->get_field_id('title'); ?>" name="<?php echo $this->get_field_name('title'); ?>" type="text" value="<?php echo $title; ?>" /></p>

    <p><input type="checkbox" class="checkbox" id="<?php echo $this->get_field_id('dropdown'); ?>" name="<?php echo $this->get_field_name('dropdown'); ?>"<?php checked( $dropdown ); ?> />
        <label for="<?php echo $this->get_field_id('dropdown'); ?>"><?php _e( 'Display as dropdown' ); ?></label><br />

        <input type="checkbox" class="checkbox" id="<?php echo $this->get_field_id('count'); ?>" name="<?php echo $this->get_field_name('count'); ?>"<?php checked( $count ); ?> />
        <label for="<?php echo $this->get_field_id('count'); ?>"><?php _e( 'Show post counts' ); ?></label><br />

        <input type="checkbox" class="checkbox" id="<?php echo $this->get_field_id('hierarchical'); ?>" name="<?php echo $this->get_field_name('hierarchical'); ?>"<?php checked( $hierarchical ); ?> />
        <label for="<?php echo $this->get_field_id('hierarchical'); ?>"><?php _e( 'Show hierarchy' ); ?></label></p>
<?php
}

}


add_action( 'widgets_init', 'ank_register_category_widget' );

function ank_register_category_widget() {
register_widget( 'Custom_Widget_Categories' );
}