Bug Version 3.8.9 widget.php

wp-content/plugins/text-slider-testimonial/textslidertestimonial.php.
There is a bug in widget.php line 51 Too few arguments to function
$text_slider_widget = ecpt_text_slider_testimonial_shortcode();

Adding $instance solves the problem
$text_slider_widget = ecpt_text_slider_testimonial_shortcode($instance);