Check null taskInfo for occlude-by-dream

Another instance of I479b05a5da896a166a375d30fdf050dc87448f3c
specific to the transition/remote animator for dream starting
over keyguard.

Test: atest android.platform.test.scenario.sysui.lockscreen
Fix: 283335509
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:826c7820829bd1e833d920071a2bb0b88d072de3)
Merged-In: I731f5f10abfcc47e8a54bfa07445f25c2eb977b0
Change-Id: I731f5f10abfcc47e8a54bfa07445f25c2eb977b0
diff --git a/packages/SystemUI/src/com/android/systemui/keyguard/KeyguardService.java b/packages/SystemUI/src/com/android/systemui/keyguard/KeyguardService.java
index b8d3121..d2526df 100644
--- a/packages/SystemUI/src/com/android/systemui/keyguard/KeyguardService.java
+++ b/packages/SystemUI/src/com/android/systemui/keyguard/KeyguardService.java
@@ -141,8 +141,8 @@
             return apps.length == 0 ? TRANSIT_OLD_KEYGUARD_GOING_AWAY_ON_WALLPAPER
                     : TRANSIT_OLD_KEYGUARD_GOING_AWAY;
         } else if (type == TRANSIT_KEYGUARD_OCCLUDE) {
-            boolean isOccludeByDream = apps.length > 0 && apps[0].taskInfo.topActivityType
-                    == WindowConfiguration.ACTIVITY_TYPE_DREAM;
+            boolean isOccludeByDream = apps.length > 0 && apps[0].taskInfo != null
+                    && apps[0].taskInfo.topActivityType == WindowConfiguration.ACTIVITY_TYPE_DREAM;
             if (isOccludeByDream) return TRANSIT_OLD_KEYGUARD_OCCLUDE_BY_DREAM;
             return TRANSIT_OLD_KEYGUARD_OCCLUDE;
         } else if (type == TRANSIT_KEYGUARD_UNOCCLUDE) {