Fix NPE

Bug: 6424377
diff --git a/src/com/android/launcher2/Launcher.java b/src/com/android/launcher2/Launcher.java
index 8b6fee9..5018806 100644
--- a/src/com/android/launcher2/Launcher.java
+++ b/src/com/android/launcher2/Launcher.java
@@ -2831,7 +2831,9 @@
             if (voiceButtonContainer != null) voiceButtonContainer.setVisibility(View.GONE);
             searchButton.setVisibility(View.GONE);
             voiceButton.setVisibility(View.GONE);
-            voiceButtonProxy.setVisibility(View.GONE);
+            if (voiceButtonProxy != null) {
+                voiceButtonProxy.setVisibility(View.GONE);
+            }
             return false;
         }
     }