From 405d8cf8ebd3f6c9c2a5f7e19c2a687235ec0a18 Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <nathansa@microsoft.com>
Date: Mon, 9 Oct 2017 10:45:50 -0700
Subject: [PATCH] In getSuggestionForNonexistentSymbol, guard name against
 undefined

---
 src/compiler/checker.ts | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index a8e18c432a6..738a484d254 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -15064,7 +15064,10 @@ namespace ts {
 
         function getSuggestionForNonexistentSymbol(location: Node, name: __String, meaning: SymbolFlags): string {
             const result = resolveNameHelper(location, name, meaning, /*nameNotFoundMessage*/ undefined, name, /*isUse*/ false, (symbols, name, meaning) => {
-                // `name` from the callback === the outer `name`
+                // NOTE: `name` from the callback is supposed to  === the outer `name`, but is undefined in some cases
+                if (name === undefined) {
+                    return undefined;
+                }
                 const symbol = getSymbol(symbols, name, meaning);
                 // Sometimes the symbol is found when location is a return type of a function: `typeof x` and `x` is declared in the body of the function
                 // So the table *contains* `x` but `x` isn't actually in scope.