From a5e184118088342db9db79c49f6cb95e53f63b72 Mon Sep 17 00:00:00 2001
From: Andrew Casey <andrew.casey@microsoft.com>
Date: Thu, 5 Oct 2017 15:37:47 -0700
Subject: [PATCH] Handle undefined in getSynthesizedClone

---
 src/compiler/factory.ts | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/compiler/factory.ts b/src/compiler/factory.ts
index 968144c0fc7..fe183c5e806 100644
--- a/src/compiler/factory.ts
+++ b/src/compiler/factory.ts
@@ -47,10 +47,15 @@ namespace ts {
      * Creates a shallow, memberwise clone of a node with no source map location.
      */
     /* @internal */
-    export function getSynthesizedClone<T extends Node>(node: T | undefined): T {
+    export function getSynthesizedClone<T extends Node>(node: T | undefined): T | undefined {
         // We don't use "clone" from core.ts here, as we need to preserve the prototype chain of
         // the original node. We also need to exclude specific properties and only include own-
         // properties (to skip members already defined on the shared prototype).
+
+        if (node === undefined) {
+            return undefined;
+        }
+
         const clone = <T>createSynthesizedNode(node.kind);
         clone.flags |= node.flags;
         setOriginalNode(clone, node);