From fbda0bdd94498d47cb4f5078565f2b6d1447e9c9 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Tue, 8 Mar 2016 11:46:47 -0800
Subject: [PATCH] Adding another check for undefined

---
 src/compiler/checker.ts | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index f18239d5e74..e2c57ffeaa1 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -7165,7 +7165,11 @@ namespace ts {
             if (!leftmostIdentifier) {
                 return type;
             }
-            const declaration = getExportSymbolOfValueSymbolIfExported(getResolvedSymbol(leftmostIdentifier)).valueDeclaration;
+            const leftmostSymbol = getExportSymbolOfValueSymbolIfExported(getResolvedSymbol(leftmostIdentifier));
+            if (!leftmostSymbol) {
+                return type;
+            }
+            const declaration = leftmostSymbol.valueDeclaration;
             if (!declaration || declaration.kind !== SyntaxKind.VariableDeclaration && declaration.kind !== SyntaxKind.Parameter && declaration.kind !== SyntaxKind.BindingElement) {
                 return type;
             }