From de10e82e8ac439c9122f71ae07d23e1a05c5b783 Mon Sep 17 00:00:00 2001
From: Ron Buckton <ron.buckton@microsoft.com>
Date: Thu, 3 May 2018 16:27:15 -0700
Subject: [PATCH] Add assertion message

---
 src/compiler/emitter.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/compiler/emitter.ts b/src/compiler/emitter.ts
index 1c5a04f60ed..f8ceaf4610f 100644
--- a/src/compiler/emitter.ts
+++ b/src/compiler/emitter.ts
@@ -486,7 +486,7 @@ namespace ts {
                     return pipelineEmitWithHint;
 
                 default:
-                    return Debug.assertNever(phase);
+                    return Debug.assertNever(phase, `Unexpected value for PipelinePhase: ${phase}`);
             }
         }