Empty toast should not be displayed

Empty toast is displayed when empty alpha identifier is specified.
If msg.txt is null, it should not be displayed.

Change-Id: I212e922a0bc4a07a8598607e320c317f86eeece3
diff --git a/src/com/android/stk/StkAppService.java b/src/com/android/stk/StkAppService.java
index 0b19f9e..c9a352b 100644
--- a/src/com/android/stk/StkAppService.java
+++ b/src/com/android/stk/StkAppService.java
@@ -1416,7 +1416,7 @@
     }
 
     private void launchEventMessage(int slotId, TextMessage msg) {
-        if (msg == null || (msg.text != null && msg.text.length() == 0)) {
+        if (msg == null || msg.text == null || (msg.text != null && msg.text.length() == 0)) {
             CatLog.d(LOG_TAG, "launchEventMessage return");
             return;
         }