Secure fetchProvidersForEmail (no providers) (#443)

packages/firebase_auth/CHANGELOG.md

diff --git a/packages/firebase_auth/CHANGELOG.md b/packages/firebase_auth/CHANGELOG.md
index c45da5c..479d676 100644
--- a/packages/firebase_auth/CHANGELOG.md
+++ b/packages/firebase_auth/CHANGELOG.md
@@ -1,3 +1,7 @@
+## 0.5.3
+
+* Secure fetchProvidersForEmail (no providers)
+
 ## 0.5.2
 
 * Fixed Dart 2 type error in fetchProvidersForEmail.

packages/firebase_auth/lib/firebase_auth.dart

diff --git a/packages/firebase_auth/lib/firebase_auth.dart b/packages/firebase_auth/lib/firebase_auth.dart
index c5f28cd..6a887de 100755
--- a/packages/firebase_auth/lib/firebase_auth.dart
+++ b/packages/firebase_auth/lib/firebase_auth.dart
@@ -168,7 +168,7 @@
         'email': email,
       },
     );
-    return providers.cast<String>();
+    return providers?.cast<String>();
   }
 
   Future<void> sendPasswordResetEmail({

packages/firebase_auth/pubspec.yaml

diff --git a/packages/firebase_auth/pubspec.yaml b/packages/firebase_auth/pubspec.yaml
index 378cd04..e1dca5a 100755
--- a/packages/firebase_auth/pubspec.yaml
+++ b/packages/firebase_auth/pubspec.yaml
@@ -4,7 +4,7 @@
   and Twitter.
 author: Flutter Team <flutter-dev@googlegroups.com>
 homepage: https://github.com/flutter/plugins/tree/master/packages/firebase_auth
-version: 0.5.2
+version: 0.5.3
 
 flutter:
   plugin: