bin/magento setup:di:compile give me this error Magento version 2.2.5
Source class "\Vendor\Module\Model\PostProductsInterface" for "\Vendor\Module\Model\PostProductsRepository" generation does not exist.
please check your project folder, if you don't see the class file maybe it's deleted or there is something wrong in your magento extension installation
if the class file exist, I think it could be 3rd extension that try inject that class. you can checking again 3rd extension that already install in your magento project