“Updating Failed” error inside WordPress Editor.

I’m getting “Updating Failed” inside Element when I’m using shortcode.

This is code of my shortcode

function shortcode_field_value( $atts ) {
  if ( ! is_admin() ) {
  $atts = shortcode_atts(
      array(
          'field_name' => '',
          'link' => false
      ), $atts, 'field_value'
  );

  $post_id = get_the_ID();
  if( ! $post_id ) {
      return '';
  }

  $cache_key = 'field_value_' . $post_id . '_' . $atts['field_name'];
  $value = wp_cache_get( $cache_key );
  if( false === $value ) {
      $value = get_field( $atts['field_name'], $post_id );
      if( is_array( $value ) ) {
          $terms = array();
          foreach( $value as $term ) {
              $terms[] = $term->name;
          }
          $value = implode( ', ', $terms );
      } elseif( is_a( $value, 'WP_Term' ) ) {
          $value = $value->name;
      }
      wp_cache_set( $cache_key, $value, '', 3600 );
  }

  if( $atts['link'] ) {
    $value = sprintf( '<a href="%s">%s</a>', get_term_link( $value ), $value );
  }


  return $value;
}
}
add_shortcode( 'field_value', 'shortcode_field_value' );

Please help me find solution for this error.