diff --git a/lib/oto/commands/util/slack.dart b/lib/oto/commands/util/slack.dart
index bdedbda..13c6d7c 100644
--- a/lib/oto/commands/util/slack.dart
+++ b/lib/oto/commands/util/slack.dart
@@ -20,9 +20,15 @@ class Slack extends Command {
       if (value != null) {
         message = value as DataSlack;
       }
+    } else {
+      message = data.message;
+    }
+
+    if (message != null) {
+      await sender.send(message);
+    } else {
+      throw Exception('property or message field should not be null');
     }
-    message = data.message;
-    await sender.send(message);
 
     return simpleFuture;
   }
diff --git a/pubspec.yaml b/pubspec.yaml
index d695128..99a8bc2 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -17,6 +17,7 @@ dependencies:
     git:
      url: toki@toki-labs.com:/Volumes/Data2/git/dart_framework.git
      ref: master
+  color: ^3.0.0
 
 dev_dependencies:
   lints: ^3.0.0