vehicle: respect result of registerAsService

(cherry picked from commit e50f2efab5b1f42e6a908272458975c8bced0cdb)

Test: works with https://android-review.googlesource.com/c/358172/
Change-Id: I73bb43f0759f4e396ededf4d8ef7f13711c13276
diff --git a/automotive/vehicle/2.1/default/service.cpp b/automotive/vehicle/2.1/default/service.cpp
index 4873279..bae64fd 100644
--- a/automotive/vehicle/2.1/default/service.cpp
+++ b/automotive/vehicle/2.1/default/service.cpp
@@ -88,11 +88,17 @@
 
     Vehicle_V2_1 vehicle21(vehicleManager.get());
 
-    ALOGI("Registering as service...");
-    vehicle21.registerAsService();
-
     configureRpcThreadpool(1, true /* callerWillJoin */);
 
+    ALOGI("Registering as service...");
+    status_t status = vehicle21.registerAsService();
+
+    if (status != OK) {
+        ALOGE("Unable to register vehicle service (%d).", status);
+        return 1;
+    }
+
     ALOGI("Ready");
     joinRpcThreadpool();
+    return 1;
 }