Fix NPE of AppVersionPreferenceController

Add null check for the package info before getting the version name.

Fixes: 168333280
Test: robotests & manual
Change-Id: If2e3d220c520d30e932478836ee2ea89f936d55c

tests/robotests/src/com/android/settings/applications/appinfo/AppVersionPreferenceControllerTest.java

@@ -16,6 +16,8 @@
 
 package com.android.settings.applications.appinfo;
 
+import static com.google.common.truth.Truth.assertThat;
+
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
@@ -62,4 +64,13 @@ public class AppVersionPreferenceControllerTest {
 
         verify(mPreference).setSummary("version test1234");
     }
+
+    @Test
+    public void updateState_packageInfoNull_shouldNotCrash() {
+        when(mFragment.getPackageInfo()).thenReturn(null);
+
+        mController.updateState(mPreference);
+
+        assertThat(mController.getSummary()).isNull();
+    }
 }