plugin works with warning message

I installed and tested quickly the plugin. It works but there is a warning message in Contact Form 7 form editor but only when this plugin is activated. Warning: Parameter 1 to wpcf7_tg_pane_min_textarea() expected to be a reference, value given in C:\wamp\www\mysite4\wp-includes\plugin.php on line 496 Call Stack # Time Memory Function Location 1 0.0011 312208 {main}( ) ..\admin.php:0 2 1.4415 27823344 do_action( ) ..\admin.php:212 3 1.4415 27824800 call_user_func_array:{C:\wamp\www\mysite4\wp-includes\plugin.php:496} ( ) ..\plugin.php:496 4 1.4415 27825056 wpcf7_admin_management_page( ) ..\plugin.php:496 5 1.4432 27904488 require_once( ‘C:\wamp\www\mysite4\wp-content\plugins\contact-form-7\admin\edit-contact-form.php’ ) ..\admin.php:210 6 1.5006 27938240 do_action( ) ..\edit-contact-form.php:117 7 1.5143 27943912 call_user_func_array:{C:\wamp\www\mysite4\wp-includes\plugin.php:496} ( ) ..\plugin.php:496 https://wordpress.org/plugins/minimum-length-for-contact-form-7/