From 1e8a7e28d00734578098255705b646269aa52f2e Mon Sep 17 00:00:00 2001
From: Anders Hejlsberg <andersh@microsoft.com>
Date: Thu, 18 Feb 2016 09:13:18 -0800
Subject: [PATCH] Correct && operator to produce nullable values

---
 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 7d7290b9031..6a95162804a 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -11260,7 +11260,7 @@ namespace ts {
                 case SyntaxKind.InKeyword:
                     return checkInExpression(left, right, leftType, rightType);
                 case SyntaxKind.AmpersandAmpersandToken:
-                    return rightType;
+                    return isNullableType(leftType) ? getNullableType(rightType) : rightType;
                 case SyntaxKind.BarBarToken:
                     return getUnionType([getNonNullableType(leftType), rightType]);
                 case SyntaxKind.EqualsToken: