From 9534b2a85609f29bd56433ac53e8121670884ec5 Mon Sep 17 00:00:00 2001
From: Marina Chirchikova <marina.chirchikova@shopify.com>
Date: Tue, 26 Feb 2019 10:56:32 -0500
Subject: [PATCH] Fix Form-State List regression

Introduced in this commit: https://github.com/Shopify/quilt/pull/475/files#diff-68157ac38fbcaa003b546774b1857293R48 on line 48. The bug is that initialValue[index][fieldPath] throws an exception instead of returning undefined the way it previously did when initialValue[index] is undefined. I added an extra check to see if initialValue.index is defined and return undefined if its not.
---
 packages/react-form-state/src/components/List.tsx | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/packages/react-form-state/src/components/List.tsx b/packages/react-form-state/src/components/List.tsx
index a20262b652..9b2033e331 100644
--- a/packages/react-form-state/src/components/List.tsx
+++ b/packages/react-form-state/src/components/List.tsx
@@ -45,7 +45,8 @@ export default class List<Fields> extends React.Component<
       const innerFields: FieldDescriptors<Fields> = mapObject(
         fieldValues,
         (value, fieldPath) => {
-          const initialFieldValue = initialValue[index][fieldPath];
+          const initialFieldValue =
+            initialValue[index] && initialValue[index][fieldPath];
           return {
             value,
             onBlur,