jdk/internal/jrtfs/remote/RemoteRuntimeImageTest.java fails with java.lang.NullPointerException

jdk/internal/jrtfs/remote/RemoteRuntimeImageTest.java fails with java.lang.NullPointerException, if specified JDK8_HOME is an invalid path. It is not friendly to throw NPE, but should check and handle invalid inputs.

----------System.err:(13/796)----------
java.lang.NullPointerException
at RemoteRuntimeImageTest.getJdk8Path(RemoteRuntimeImageTest.java:108)
at RemoteRuntimeImageTest.main(RemoteRuntimeImageTest.java:58)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:564)
at com.sun.javatest.regtest.agent.MainActionHelper$SameVMRunnable.run(MainActionHelper.java:230)
at java.base/java.lang.Thread.run(Thread.java:844)