Merge "Fix NullPointer Exception in testharness command" am: 881c4ad3e2

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1674567

Change-Id: I88cbc7392fcdfc8dcdac005ae636d3ada57c28c5

services/core/java/com/android/server/testharness/TestHarnessModeService.java

@@ -286,6 +286,9 @@ public class TestHarnessModeService extends SystemService {
     private class TestHarnessModeShellCommand extends ShellCommand {
         @Override
         public int onCommand(String cmd) {
+            if (cmd == null) {
+                return handleDefaultCommands(cmd);
+            }
             switch (cmd) {
                 case "enable":
                 case "restore":