WebDriver is NULL when start more then one test case

I have a problem. Here is my code = https://github.com/Dermenji/SeleniumCourse There are 2 classes and each have 1 test case. When I start every test mannualy - is OK. But when execute tests with maven - only one test is executed successfully and as expectedm but another have java.lang.NullPointerException at com.selenium.course.tests.ProductTests.executeProductTest(ProductTests.java:17). Expected behavior: all tests are executed in every test class Please, help