From 271ca80c75e30132cc2549a79f562a2abbb432a3 Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <nathansa@microsoft.com>
Date: Mon, 13 Feb 2017 13:35:07 -0800
Subject: [PATCH] Address PR comments

---
 src/compiler/checker.ts | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 6f213355679..6f352c95aec 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -7777,8 +7777,10 @@ namespace ts {
                         return related;
                     }
                 }
-                const discriminantType = findMatchingDiscriminantType(source, target);
-                isRelatedTo(source, discriminantType || targetTypes[targetTypes.length - 1], reportErrors);
+                if (reportErrors) {
+                    const discriminantType = findMatchingDiscriminantType(source, target);
+                    isRelatedTo(source, discriminantType || targetTypes[targetTypes.length - 1], /*reportErrors*/ true);
+                }
                 return Ternary.False;
             }