From 4b0424fbed8b873d67684785bfbdf22323cb3125 Mon Sep 17 00:00:00 2001
From: Brian Vaughn <bvaughn@fb.com>
Date: Wed, 10 Apr 2019 10:16:09 -0700
Subject: [PATCH] Flow fix

---
 src/devtools/views/Components/TreeContext.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/devtools/views/Components/TreeContext.js b/src/devtools/views/Components/TreeContext.js
index 4e09ab4e02..a2dcd63f65 100644
--- a/src/devtools/views/Components/TreeContext.js
+++ b/src/devtools/views/Components/TreeContext.js
@@ -407,7 +407,7 @@ function reduceOwnersState(store: Store, state: State, action: Action): State {
             ownerStackIndex = ownerStack.length - 1;
           }
         }
-        if (selectedElementID !== null) {
+        if (selectedElementID !== null && _ownerFlatTree !== null) {
           // Mutation might have caused the index of this ID to shift.
           selectedElementIndex = _ownerFlatTree.indexOf(selectedElementID);
         }