On PS1.7.5.0 I encountered "POST
https://vaping.trade/modules/lac/ajax_lac.php 500" and "Uncaught ReferenceError: lac_module_secure_key is not defined" errors.
It worked after changing the permissions to all module files to 755 and deleting the prefix "lac_" in the secure_key code: lac_module_secure_key on the file /modules/lac/views/js/176orders.js
Attached the modified module (after installation, you need to check file permissions).
Demo:
mypresta.eu
The module adds the "Login as customer" button only to the order page and "Customer management".