Error when selecting email customer

The email have been sent to the customer.

Warning: Illegal offset type in isset or empty in /home/valconu/public_html/wp-includes/taxonomy.php on line 309

Warning: count(): Parameter must be an array or an object that implements Countable in /home/valconu/public_html/wp-content/plugins/computer-repair-shop/lib/includes/theme_functions.php on line 2602

Warning: count(): Parameter must be an array or an object that implements Countable in /home/valconu/public_html/wp-content/plugins/computer-repair-shop/lib/includes/theme_functions.php on line 2602

Hey it looks like the device you are using is not attached to any brand yet, 

Please note: each device have to be attached with a brand otherwise you will ahve these issues. 

Please go to Devices page and see which devices do not have brand defined. 

Select checkbox on left for all those devices. 

Then click on Quick edit to add brand to all otherwise edit one by one for different brands. 

If you still have confusion you may send me your WordPress logins to view thanks.