From 7d8f21a63b9fd1c617aa85a8679be251461d9f39 Mon Sep 17 00:00:00 2001
From: Christian Kohler <kohler.christian@gmail.com>
Date: Mon, 18 Feb 2019 14:25:36 +0100
Subject: [PATCH 1/2] fix(Subscription): Return Empty when teardown === null

`typeof teardown` returns object when null. It breaks later when rxjs tries to access the closed property.

The commit fixes that by first checking for null/undefined.
---
 src/internal/Subscription.ts | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/internal/Subscription.ts b/src/internal/Subscription.ts
index 0f1906a27e..df5a91d02f 100644
--- a/src/internal/Subscription.ts
+++ b/src/internal/Subscription.ts
@@ -130,6 +130,11 @@ export class Subscription implements SubscriptionLike {
    */
   add(teardown: TeardownLogic): Subscription {
     let subscription = (<Subscription>teardown);
+    
+    if (!(<any>teardown)) {
+      return Subscription.EMPTY;
+    }
+    
     switch (typeof teardown) {
       case 'function':
         subscription = new Subscription(<(() => void)>teardown);
@@ -147,9 +152,6 @@ export class Subscription implements SubscriptionLike {
         }
         break;
       default: {
-        if (!(<any>teardown)) {
-          return Subscription.EMPTY;
-        }
         throw new Error('unrecognized teardown ' + teardown + ' added to Subscription.');
       }
     }

From c4a8bc0a6a6f26ceac4cfc0cd7562c48c2040f62 Mon Sep 17 00:00:00 2001
From: Chris <chris@Chriss-MacBook-Pro.local>
Date: Mon, 18 Feb 2019 14:53:45 +0100
Subject: [PATCH 2/2] fix(Subscription): tslint errors

---
 src/internal/Subscription.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/internal/Subscription.ts b/src/internal/Subscription.ts
index df5a91d02f..1a07ffa508 100644
--- a/src/internal/Subscription.ts
+++ b/src/internal/Subscription.ts
@@ -130,11 +130,11 @@ export class Subscription implements SubscriptionLike {
    */
   add(teardown: TeardownLogic): Subscription {
     let subscription = (<Subscription>teardown);
-    
+
     if (!(<any>teardown)) {
       return Subscription.EMPTY;
     }
-    
+
     switch (typeof teardown) {
       case 'function':
         subscription = new Subscription(<(() => void)>teardown);