Fix NPE in STK application.

Fix NullPointerException while handling "refresh" command.

Bug: 5451736
Change-Id: I10f8382527193d5240715559d97ef6c06ceb1672
diff --git a/src/com/android/stk/StkAppService.java b/src/com/android/stk/StkAppService.java
index 0ffb9c8..7fd639f 100644
--- a/src/com/android/stk/StkAppService.java
+++ b/src/com/android/stk/StkAppService.java
@@ -703,6 +703,10 @@
 
     private void launchIdleText() {
         TextMessage msg = mCurrentCmd.geTextMessage();
+        if (msg == null) {
+            CatLog.d(this, "mCurrentCmd.getTextMessage is NULL");
+            return;
+        }
         if (msg.text == null) {
             mNotificationManager.cancel(STK_NOTIFICATION_ID);
         } else {