[run-test-component] fail on premature exit

Change-Id: Ib35d2fa7eeba5ea41268bad49dea13f709ade52c
diff --git a/garnet/bin/run_test_component/main.cc b/garnet/bin/run_test_component/main.cc
index 4a80cd4..1ac46e4 100644
--- a/garnet/bin/run_test_component/main.cc
+++ b/garnet/bin/run_test_component/main.cc
@@ -233,5 +233,6 @@
   };
 
   loop.Run();
-  return 0;
+  fprintf(stderr, "run-test-component: premature loop exit\n");
+  return 1;
 }