Add NullPtrCheck when smearing in settings

This only happens in new device with broken power_profile.xml, in
which it doesn't have screen power model.

This CL catches the null pointer crash and log it.

Change-Id: Iac23e3a8fc51385bdb22979c4b59000319f6fd49
Fixes: 74617269
Test: RunSettingsRoboTests

tests/robotests/src/com/android/settings/fuelgauge/BatteryUtilsTest.java

@@ -376,6 +376,18 @@ public class BatteryUtilsTest {
                 BATTERY_APP_USAGE + BATTERY_SCREEN_USAGE / 2);
     }
 
+    @Test
+    public void testSmearScreenBatterySipper_screenSipperNull_shouldNotCrash() {
+        final BatterySipper sipperFg = createTestSmearBatterySipper(TIME_FOREGROUND,
+                BATTERY_APP_USAGE, 2 /* uid */, false /* isUidNull */);
+
+        final List<BatterySipper> sippers = new ArrayList<>();
+        sippers.add(sipperFg);
+
+        // Shouldn't crash
+        mBatteryUtils.smearScreenBatterySipper(sippers, null /* screenSipper */);
+    }
+
     @Test
     public void testCalculateRunningTimeBasedOnStatsType() {
         assertThat(mBatteryUtils.calculateRunningTimeBasedOnStatsType(mBatteryStatsHelper,