I am using HelloWear theme on Magento 22.214.171.124. I have no problems with the theme (I like it a lot), but having problems installing 3rd party extensions. Every time I am trying installing an extension, it breaks the admin site. I am getting an error like
Fatal error: Class "XXX_YYY_Helper_Data' not found.
I created test site that has the same functionality but does not use the HelloWear theme. I can install any extension on this site with no problems.
Can someone suggest how HelloWear theme may interfere with 3rd party extensions?