From 23a1dd4d742e1849a87373927e06b463abe659c6 Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Thu, 15 Sep 2022 16:19:58 -0700
Subject: [PATCH] Fix bounds check

---
 src/compiler/checker.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 6916eede2f4..90e0a9eabee 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -36043,8 +36043,8 @@ namespace ts {
         }
 
         function getEffectiveTypeArgumentAtIndex(node: TypeReferenceNode | ExpressionWithTypeArguments, typeParameters: readonly TypeParameter[], index: number): Type {
-            if (index < typeParameters.length) {
-                return getTypeFromTypeNode(node.typeArguments![index]);
+            if (node.typeArguments && index < node.typeArguments.length) {
+                return getTypeFromTypeNode(node.typeArguments[index]);
             }
             return getEffectiveTypeArguments(node, typeParameters)[index];
         }