From 5ce6623ec026b8f5518ad27ed84bc2e52d81f049 Mon Sep 17 00:00:00 2001
From: Bruno Lemos <brunolemos@users.noreply.github.com>
Date: Fri, 13 Apr 2018 23:58:30 -0300
Subject: [PATCH] Fix: undefined is not an object (evaluating
 sceneConfig.animationInterpolators)

Fix https://github.com/facebook/react-native/issues/12742
---
 src/Navigator.js | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/src/Navigator.js b/src/Navigator.js
index 08f51df..b41bf96 100644
--- a/src/Navigator.js
+++ b/src/Navigator.js
@@ -1000,9 +1000,7 @@ var Navigator = createReactClass({
 
   _transitionSceneStyle: function(fromIndex, toIndex, progress, index) {
     var viewAtIndex = this._sceneRefs[index];
-    if (viewAtIndex === null || viewAtIndex === undefined) {
-      return;
-    }
+    if (!viewAtIndex) return;
     // Use toIndex animation when we move forwards. Use fromIndex when we move back
     var sceneConfigIndex = fromIndex < toIndex ? toIndex : fromIndex;
     var sceneConfig = this.state.sceneConfigStack[sceneConfigIndex];
@@ -1010,6 +1008,7 @@ var Navigator = createReactClass({
     if (!sceneConfig) {
       sceneConfig = this.state.sceneConfigStack[sceneConfigIndex - 1];
     }
+    if (!sceneConfig) return;
     var styleToUse = {};
     var useFn = index < fromIndex || index < toIndex ?
       sceneConfig.animationInterpolators.out :