Customised core file – coupons don't load in 5.7

Hello all

I have some customisation in my Class_white_label_themes file to create a button next to the Small List view. When I apply this file in the 5.7 update (by overwriting the same name file in the class folder) my coupons don’t work anymore when you click on them.
I click on the title and the page doesn’t load. Any idea how I can fix this?

The customized file is attached.

Thanks
Jasper