Fix an NPE

Bug: 6538761
Change-Id: Id85486ee93437cfec7db421d5c7f2d7980a7e32e
diff --git a/java/src/com/android/inputmethod/latin/LatinIME.java b/java/src/com/android/inputmethod/latin/LatinIME.java
index 139eb46..83658f7 100644
--- a/java/src/com/android/inputmethod/latin/LatinIME.java
+++ b/java/src/com/android/inputmethod/latin/LatinIME.java
@@ -2299,7 +2299,7 @@
             final InputConnection ic = getCurrentInputConnection();
             if (null != ic) {
                 final CharSequence lastChar = ic.getTextBeforeCursor(1, 0);
-                if (lastChar.length() > 0 && Character.isHighSurrogate(lastChar.charAt(0))) {
+                if (!TextUtils.isEmpty(lastChar) && Character.isHighSurrogate(lastChar.charAt(0))) {
                     ic.deleteSurroundingText(1, 0);
                 }
             }