Fix NPE

Follow up to I2b0ec091a11aa8a495794d633efecb6d8b818f42

bug: 14488351
Change-Id: Ic88adbd6775910f35338d798dc0d5493715708e4
diff --git a/java/src/com/android/inputmethod/keyboard/KeyboardSwitcher.java b/java/src/com/android/inputmethod/keyboard/KeyboardSwitcher.java
index 589e99e..1cd6ef2 100644
--- a/java/src/com/android/inputmethod/keyboard/KeyboardSwitcher.java
+++ b/java/src/com/android/inputmethod/keyboard/KeyboardSwitcher.java
@@ -147,7 +147,9 @@
 
     public void onHideWindow() {
         mIsAutoCorrectionActive = false;
-        mKeyboardView.onHideWindow();
+        if (mKeyboardView != null) {
+            mKeyboardView.onHideWindow();
+        }
     }
 
     private void setKeyboard(final Keyboard keyboard) {