--- a/dom/workers/ServiceWorkerContainer.cpp
+++ b/dom/workers/ServiceWorkerContainer.cpp
@@ -208,20 +208,18 @@ ServiceWorkerContainer::Register(const n
     aRv = CheckForSlashEscapedCharsInPath(scopeURI);
     if (NS_WARN_IF(aRv.Failed())) {
       return nullptr;
     }
   }
 
   // The spec says that the "client" passed to Register() must be the global
   // where the ServiceWorkerContainer was retrieved from.
-  nsCOMPtr<nsPIDOMWindow> window = GetOwner();
-  MOZ_ASSERT(window);
-  aRv = swm->Register(window, scopeURI, scriptURI, getter_AddRefs(promise));
-  if (aRv.Failed()) {
+  aRv = swm->Register(GetOwner(), scopeURI, scriptURI, getter_AddRefs(promise));
+  if (NS_WARN_IF(aRv.Failed())) {
     return nullptr;
   }
 
   RefPtr<Promise> ret = static_cast<Promise*>(promise.get());
   MOZ_ASSERT(ret);
   return ret.forget();
 }
 
@@ -323,14 +321,26 @@ ServiceWorkerContainer::GetScopeForUrl(c
                                        ErrorResult& aRv)
 {
   nsCOMPtr<nsIServiceWorkerManager> swm = mozilla::services::GetServiceWorkerManager();
   if (!swm) {
     aRv.Throw(NS_ERROR_FAILURE);
     return;
   }
 
-  aRv = swm->GetScopeForUrl(GetOwner()->GetExtantDoc()->NodePrincipal(),
+  nsCOMPtr<nsPIDOMWindow> window = GetOwner();
+  if (NS_WARN_IF(!window)) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return;
+  }
+
+  nsCOMPtr<nsIDocument> doc = window->GetExtantDoc();
+  if (NS_WARN_IF(!doc)) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return;
+  }
+
+  aRv = swm->GetScopeForUrl(doc->NodePrincipal(),
                             aUrl, aScope);
 }
 
 } // namespace dom
 } // namespace mozilla

--- a/dom/workers/ServiceWorkerManager.cpp
+++ b/dom/workers/ServiceWorkerManager.cpp
@@ -1410,17 +1410,19 @@ NS_IMETHODIMP
 ServiceWorkerManager::Register(nsIDOMWindow* aWindow,
                                nsIURI* aScopeURI,
                                nsIURI* aScriptURI,
                                nsISupports** aPromise)
 {
   AssertIsOnMainThread();
 
   nsCOMPtr<nsPIDOMWindow> window = do_QueryInterface(aWindow);
-  MOZ_ASSERT(window);
+  if (NS_WARN_IF(!window)) {
+    return NS_ERROR_DOM_INVALID_STATE_ERR;
+  }
 
   nsCOMPtr<nsIDocument> doc = window->GetExtantDoc();
   if (!doc) {
     return NS_ERROR_FAILURE;
   }
 
   // Don't allow service workers to register when the *document* is chrome for
   // now.
@@ -1715,24 +1717,25 @@ public:
 
 // If we return an error code here, the ServiceWorkerContainer will
 // automatically reject the Promise.
 NS_IMETHODIMP
 ServiceWorkerManager::GetRegistrations(nsIDOMWindow* aWindow,
                                        nsISupports** aPromise)
 {
   AssertIsOnMainThread();
-  MOZ_ASSERT(aWindow);
 
   nsCOMPtr<nsPIDOMWindow> window = do_QueryInterface(aWindow);
-  MOZ_ASSERT(window);
+  if (NS_WARN_IF(!window)) {
+    return NS_ERROR_DOM_INVALID_STATE_ERR;
+  }
 
   nsCOMPtr<nsIDocument> doc = window->GetExtantDoc();
-  if (!doc) {
-    return NS_ERROR_FAILURE;
+  if (NS_WARN_IF(!doc)) {
+    return NS_ERROR_DOM_INVALID_STATE_ERR;
   }
 
   // Don't allow service workers to register when the *document* is chrome for
   // now.
   MOZ_ASSERT(!nsContentUtils::IsSystemPrincipal(doc->NodePrincipal()));
 
   nsCOMPtr<nsIGlobalObject> sgo = do_QueryInterface(window);
   ErrorResult result;
@@ -1819,24 +1822,25 @@ public:
 // If we return an error code here, the ServiceWorkerContainer will
 // automatically reject the Promise.
 NS_IMETHODIMP
 ServiceWorkerManager::GetRegistration(nsIDOMWindow* aWindow,
                                       const nsAString& aDocumentURL,
                                       nsISupports** aPromise)
 {
   AssertIsOnMainThread();
-  MOZ_ASSERT(aWindow);
 
   nsCOMPtr<nsPIDOMWindow> window = do_QueryInterface(aWindow);
-  MOZ_ASSERT(window);
+  if (NS_WARN_IF(!window)) {
+    return NS_ERROR_DOM_INVALID_STATE_ERR;
+  }
 
   nsCOMPtr<nsIDocument> doc = window->GetExtantDoc();
-  if (!doc) {
-    return NS_ERROR_FAILURE;
+  if (NS_WARN_IF(!doc)) {
+    return NS_ERROR_DOM_INVALID_STATE_ERR;
   }
 
   // Don't allow service workers to register when the *document* is chrome for
   // now.
   MOZ_ASSERT(!nsContentUtils::IsSystemPrincipal(doc->NodePrincipal()));
 
   nsCOMPtr<nsIGlobalObject> sgo = do_QueryInterface(window);
   ErrorResult result;
@@ -1972,23 +1976,24 @@ ServiceWorkerManager::SendNotificationCl
                                                    NS_ConvertUTF8toUTF16(aScope));
 }
 
 NS_IMETHODIMP
 ServiceWorkerManager::GetReadyPromise(nsIDOMWindow* aWindow,
                                       nsISupports** aPromise)
 {
   AssertIsOnMainThread();
-  MOZ_ASSERT(aWindow);
 
   nsCOMPtr<nsPIDOMWindow> window = do_QueryInterface(aWindow);
-  MOZ_ASSERT(window);
+  if (NS_WARN_IF(!window)) {
+    return NS_ERROR_DOM_INVALID_STATE_ERR;
+  }
 
   nsCOMPtr<nsIDocument> doc = window->GetExtantDoc();
-  if (!doc) {
+  if (NS_WARN_IF(!doc)) {
     return NS_ERROR_FAILURE;
   }
 
   // Don't allow service workers to register when the *document* is chrome for
   // now.
   MOZ_ASSERT(!nsContentUtils::IsSystemPrincipal(doc->NodePrincipal()));
 
   MOZ_ASSERT(!mPendingReadyPromises.Contains(window));
@@ -2910,17 +2915,17 @@ ServiceWorkerManager::GetServiceWorkerFo
                                                const nsAString& aScope,
                                                WhichServiceWorker aWhichWorker,
                                                nsISupports** aServiceWorker)
 {
   AssertIsOnMainThread();
 
   nsCOMPtr<nsPIDOMWindow> window = do_QueryInterface(aWindow);
   if (NS_WARN_IF(!window)) {
-    return NS_ERROR_FAILURE;
+    return NS_ERROR_DOM_INVALID_STATE_ERR;
   }
 
   nsCOMPtr<nsIDocument> doc = window->GetExtantDoc();
   MOZ_ASSERT(doc);
 
   ///////////////////////////////////////////
   // Security check
   nsAutoCString scope = NS_ConvertUTF16toUTF8(aScope);
@@ -3175,17 +3180,17 @@ ServiceWorkerManager::GetDocumentRegistr
  */
 NS_IMETHODIMP
 ServiceWorkerManager::GetDocumentController(nsIDOMWindow* aWindow,
                                             nsISupports** aServiceWorker)
 {
   nsCOMPtr<nsPIDOMWindow> window = do_QueryInterface(aWindow);
   MOZ_ASSERT(window);
   if (!window || !window->GetExtantDoc()) {
-    return NS_ERROR_FAILURE;
+    return NS_ERROR_DOM_INVALID_STATE_ERR;
   }
 
   nsCOMPtr<nsIDocument> doc = window->GetExtantDoc();
 
   RefPtr<ServiceWorkerRegistrationInfo> registration;
   nsresult rv = GetDocumentRegistration(doc, getter_AddRefs(registration));
   if (NS_WARN_IF(NS_FAILED(rv))) {
     return rv;

--- a/dom/workers/ServiceWorkerRegistration.cpp
+++ b/dom/workers/ServiceWorkerRegistration.cpp
@@ -684,17 +684,16 @@ ServiceWorkerRegistrationMainThread::Unr
 // Notification API extension.
 already_AddRefed<Promise>
 ServiceWorkerRegistrationMainThread::ShowNotification(JSContext* aCx,
                                                       const nsAString& aTitle,
                                                       const NotificationOptions& aOptions,
                                                       ErrorResult& aRv)
 {
   AssertIsOnMainThread();
-  MOZ_ASSERT(GetOwner());
   nsCOMPtr<nsPIDOMWindow> window = GetOwner();
   if (NS_WARN_IF(!window)) {
     aRv.Throw(NS_ERROR_FAILURE);
     return nullptr;
   }
 
   nsCOMPtr<nsIDocument> doc = window->GetExtantDoc();
   if (NS_WARN_IF(!doc)) {
@@ -719,16 +718,20 @@ ServiceWorkerRegistrationMainThread::Sho
   return p.forget();
 }
 
 already_AddRefed<Promise>
 ServiceWorkerRegistrationMainThread::GetNotifications(const GetNotificationOptions& aOptions, ErrorResult& aRv)
 {
   AssertIsOnMainThread();
   nsCOMPtr<nsPIDOMWindow> window = GetOwner();
+  if (NS_WARN_IF(!window)) {
+    aRv.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
+    return nullptr;
+  }
   return Notification::Get(window, aOptions, mScope, aRv);
 }
 
 already_AddRefed<PushManager>
 ServiceWorkerRegistrationMainThread::GetPushManager(ErrorResult& aRv)
 {
   AssertIsOnMainThread();