Handle empty reply

pkg/cli/cmd.go

@@ -236,6 +236,9 @@ var replyCmd = &cobra.Command{
 		}
 
 		messageContents, err := InputFromEditor("# How would you like to reply?\n", "reply.*.md")
+		if messageContents == "" {
+			Fatal("No reply was provided.\n")
+		}
 
 		userReply := Message{
 			ConversationID:  conversation.ID,