Fixing crash when using app name comparator with empty titles.

Bug: 22065752
Change-Id: I4160f5e1728e46ce85fd2579889e7952de01a752
diff --git a/src/com/android/launcher3/model/AppNameComparator.java b/src/com/android/launcher3/model/AppNameComparator.java
index cd45d2c..c4b74d4 100644
--- a/src/com/android/launcher3/model/AppNameComparator.java
+++ b/src/com/android/launcher3/model/AppNameComparator.java
@@ -85,8 +85,10 @@
      */
     @Thunk int compareTitles(String titleA, String titleB) {
         // Ensure that we de-prioritize any titles that don't start with a linguistic letter or digit
-        boolean aStartsWithLetter = Character.isLetterOrDigit(titleA.codePointAt(0));
-        boolean bStartsWithLetter = Character.isLetterOrDigit(titleB.codePointAt(0));
+        boolean aStartsWithLetter = (titleA.length() > 0) &&
+                Character.isLetterOrDigit(titleA.codePointAt(0));
+        boolean bStartsWithLetter = (titleB.length() > 0) &&
+                Character.isLetterOrDigit(titleB.codePointAt(0));
         if (aStartsWithLetter && !bStartsWithLetter) {
             return -1;
         } else if (!aStartsWithLetter && bStartsWithLetter) {