Don't attempt to write to stdout or stderr after stream is closed (#6)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 9db945d..cc43eb1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md

@@ -1,3 +1,8 @@
+#### 2.0.1
+
+* Fixed bug in `ReplayProcessManager` whereby it could try to write to `stdout`
+  or `stderr` after the streams were closed.
+
 #### 2.0.0
 
 * Bumped `package:file` dependency to 2.0.1

diff --git a/lib/src/record_replay/replay_process_manager.dart b/lib/src/record_replay/replay_process_manager.dart
index bef2343..6203598 100644
--- a/lib/src/record_replay/replay_process_manager.dart
+++ b/lib/src/record_replay/replay_process_manager.dart

@@ -73,7 +73,7 @@
     File manifestFile = fs.file(path.join(location.path, kManifestName));
     if (!manifestFile.existsSync()) {
       throw new ArgumentError.value(
-          location, 'location', 'Does not represent a valid recording.');
+          location, 'location', 'Does not represent a valid recording');
     }
 
     String content = await manifestFile.readAsString();
@@ -288,8 +288,12 @@
     // Don't flush our stdio streams until we at least reach the outer event
     // loop. i.e. even if `streamDelay` is zero, we still want to use the timer.
     new Timer(result.manager.streamDelay, () {
-      _stdoutController.add(_stdout);
-      _stderrController.add(_stderr);
+      if (!_stdoutController.isClosed) {
+        _stdoutController.add(_stdout);
+      }
+      if (!_stderrController.isClosed) {
+        _stderrController.add(_stderr);
+      }
       if (!daemon) kill();
     });
   }

diff --git a/pubspec.yaml b/pubspec.yaml
index debb5a7..75e0544 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml

@@ -1,5 +1,5 @@
 name: process
-version: 2.0.0
+version: 2.0.1
 authors:
 - Todd Volkert <tvolkert@google.com>
 - Michael Goderbauer <goderbauer@google.com>