Merge "Fix null dereference in WMShell transition" into main am: 91dcf18eb0

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/3220823

Change-Id: Ibe4987c990ca9ffe9210fd1f16f043e99ace87a4
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/transition/Transitions.java b/libs/WindowManager/Shell/src/com/android/wm/shell/transition/Transitions.java
index d2e6a12..c3a70bb 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/transition/Transitions.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/transition/Transitions.java
@@ -724,7 +724,11 @@
                 Log.e(TAG, "Got duplicate transitionReady for " + transitionToken);
                 // The transition is already somewhere else in the pipeline, so just return here.
                 t.apply();
-                existing.mFinishT.merge(finishT);
+                if (existing.mFinishT != null) {
+                    existing.mFinishT.merge(finishT);
+                } else {
+                    existing.mFinishT = finishT;
+                }
                 return;
             }
             // This usually means the system is in a bad state and may not recover; however,