Php notice to get property 'sender' non-object in

Hi!
For a few months i noticed that when you click on the icon "email this link to a friend" on my site, it does not work.
I opened my error_log file and i have found lot of error messages. These are some of them:
PHP Notice: Trying to get property 'link' of non-object in /xxxx/yyyy/public_html/plugins/system/yjsg/legacy/html/com_mailto/mailto/default.php on line 40
PHP Notice: Trying to get property 'link' of non-object in /xxxx/yyyy/public_html/plugins/system/yjsg/legacy/html/com_mailto/mailto/default.php on line50
PHP Notice: Trying to get property 'link' of non-object in /xxxx/yyyy/public_html/plugins/system/yjsg/legacy/html/com_mailto/mailto/default.php on line 55
PHP Notice: Trying to get property 'link' of non-object in /xxxx/yyyy/public_html/plugins/system/yjsg/legacy/html/com_mailto/mailto/default.php on line 69
I have joomla 3.9 and the latest yjsg available(update applied les than 7 days ago)

Does anyone know how to fix this ?

Are you sure your are posting in product assigned forum?: Yes

What is your CMS version?: Joomla 3.x

MySQL Version: 5.x

PHP version: N/A

Link to installation: fcwc-fish.org

Have you edited any files? If yes tell us which ones.: No

Is this personal or client website?: Client

Are you sure your are posting in product assigned forum?: Yes

What is your CMS version?: Joomla 3.x

MySQL Version: 5.x

PHP version: N/A

Link to installation: http://fcwc-fish.org

Have you edited any files? If yes tell us which ones.: No

Is this personal or client website?: Client

What template are you using?
The legacy is for very old templates 2014 and before

https://github.com/YJSGframework/yjs...class.php#L265

Thank for your reply
I'm using YOUGRIDS 2.0.0 and YJSG Plugin v2.3.4 is installed and published.
Please see attached screenshot!
Do I have to remove and re-install the template ?
If yes, is there anyway to export the settings and import them after installation ?