From 3f5f8d7bd6f26daa0758fc8ce8bf8ed9b0cd7cd3 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Fri, 25 May 2018 09:45:53 -0700
Subject: [PATCH] Fix issue

---
 src/compiler/checker.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 8164dc14d55..d1ede654a3d 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -8610,7 +8610,7 @@ namespace ts {
             if (!strictNullChecks && includes & TypeFlags.Nullable) {
                 return includes & TypeFlags.Undefined ? undefinedType : nullType;
             }
-            if (types.length === 0) {
+            if (typeSet.length === 0) {
                 return includes & TypeFlags.TopUnion ? getTopType() : emptyObjectType;
             }
             if (includes & TypeFlags.String && includes & TypeFlags.StringLiteral ||