From d45806a9844d7495c0cc25e70aff637cbf9b16fd Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Sun, 23 May 2021 17:03:11 -0700
Subject: [PATCH] More closely match previous behavior

---
 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 d64d1e5da3b..ff3ec78a931 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -24122,7 +24122,7 @@ namespace ts {
         }
 
         function isGenericTypeWithUnionConstraint(type: Type) {
-            return !!(type.flags & TypeFlags.Instantiable && getBaseConstraintOrType(type).flags & TypeFlags.Union);
+            return !!(type.flags & TypeFlags.Instantiable && getBaseConstraintOrType(type).flags & (TypeFlags.Nullable | TypeFlags.Union));
         }
 
         function containsGenericType(type: Type): boolean {