Do not allow activity to get posted without any Media

functions.php

/**
 * Add content into the post
 */
function acrosswp_nouveau_ajax_post_update_custom() {

  if ( ! is_user_logged_in() || empty( $_POST['_wpnonce_post_update'] ) || ! wp_verify_nonce( $_POST['_wpnonce_post_update'], 'post_update' ) ) {
    wp_send_json_error();
	}

  // check activity toolbar options if one of them is set, activity can be empty.
  $toolbar_option = false;
  if ( bp_is_active( 'media' ) && ! empty( $_POST['document'] ) ) {
    $toolbar_option = true;
  } elseif ( bp_is_active( 'media' ) && ! empty( $_POST['media'] ) ) {
    $toolbar_option = true;
  } elseif ( bp_is_activity_link_preview_active() && ! empty( $_POST['link_url'] ) ) {
    $toolbar_option = true;
  } elseif ( bp_is_active( 'media' ) && ! empty( $_POST['gif_data'] ) ) {
    $toolbar_option = true;
  } elseif ( bp_is_active( 'video' ) && ! empty( $_POST['video'] ) ) {
    $toolbar_option = true;
  }

  if ( ! $toolbar_option ) {
    wp_send_json_error(
      array(
        'message' => __( 'Please enter some media to post.', 'buddyboss' ),
      )
    );
  }

}
add_action( 'wp_ajax_post_update', 'acrosswp_nouveau_ajax_post_update_custom', -1 );