Class not found error

Hello,

I’m receiving the following error after updating to 4.0.1:
Fatal error: Uncaught Error: Class ‘Testimonials_Widget’ not found in /Users/XXX/AAA/BBB/app/public/wp-content/themes/CCC/testimonials-widget/testimonial-content.php on line 10

Here’s the snippet the error is referencing:
$char_limit = $atts[‘char_limit’];
$content_more = apply_filters( ‘tw_content_more’, esc_html__( ‘…’, ‘testimonials-widget’ ) );
$content_more .= Testimonials_Widget::$tag_close_quote;
$do_content = ! $atts[‘hide_content’] && ! empty( $testimonial[‘testimonial_content’] );
$testimonial_id = $tw_template_args[‘testimonial’][‘post_id’];

Has anyone else seen this issue or have a suggestion on how to fix?

Thanks!