Register widget with wrapping the widget content

functions.php

function pana_widgets_init() {
	register_sidebar( array(
		'name'          => 'سایدبار پست',
		'id'            => 'post_sidebar',
		'description'   => 'در این سایدبار می توایند به تعداد دلخواه ابزارک قرار دهید',
		'before_widget' => '<section id="%1$s" class="widget %2$s">',
		'after_widget'  => '</div></section>',
		'before_title'  => '<h2 class="widget-title">',
		'after_title'   => '</h2><div class="widget-content">',
	) );


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


// if no title then add widget content wrapper to before widget
add_filter( 'dynamic_sidebar_params', 'check_sidebar_params' );
function check_sidebar_params( $params ) {
    global $wp_registered_widgets;

    $settings_getter = $wp_registered_widgets[ $params[0]['widget_id'] ]['callback'][0];
    $settings = $settings_getter->get_settings();
    $settings = $settings[ $params[1]['number'] ];

    if ( $params[0][ 'after_widget' ] == '</div></section>' && isset( $settings[ 'title' ] ) && empty( $settings[ 'title' ] ) )
        $params[0][ 'before_widget' ] .= '<div class="widget-content">';

    return $params;
}