From e54e865c34077a816acf4c6653a6531a59781828 Mon Sep 17 00:00:00 2001
From: Dzmitry Shylovich <DmitryShilovich@gmail.com>
Date: Tue, 7 Mar 2017 10:31:28 +0300
Subject: [PATCH] fix(core): stringify shouldn't throw when toString returns
 null/undefined (#14975)

Fixes #14948

PR Close #14975
---
 packages/core/src/util.ts       |  5 +++++
 packages/core/test/util_spec.ts | 19 +++++++++++++++++++
 2 files changed, 24 insertions(+)
 create mode 100644 packages/core/test/util_spec.ts

diff --git a/packages/core/src/util.ts b/packages/core/src/util.ts
index 217bb6ffff4f3..800f57109178d 100644
--- a/packages/core/src/util.ts
+++ b/packages/core/src/util.ts
@@ -69,6 +69,11 @@ export function stringify(token: any): string {
   }
 
   const res = token.toString();
+
+  if (res == null) {
+    return '' + res;
+  }
+
   const newLineIndex = res.indexOf('\n');
   return newLineIndex === -1 ? res : res.substring(0, newLineIndex);
 }
diff --git a/packages/core/test/util_spec.ts b/packages/core/test/util_spec.ts
new file mode 100644
index 0000000000000..f1138eaa69d21
--- /dev/null
+++ b/packages/core/test/util_spec.ts
@@ -0,0 +1,19 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import {stringify} from '../src/util';
+
+export function main() {
+  describe('stringify', () => {
+    it('should return string undefined when toString returns undefined',
+       () => expect(stringify({toString: (): string => undefined})).toBe('undefined'));
+
+    it('should return string null when toString returns null',
+       () => expect(stringify({toString: (): string => null})).toBe('null'));
+  });
+}