From a7523015f7f67a8023605a26600915eb05ef4316 Mon Sep 17 00:00:00 2001
From: Jae Kwon <jae@tendermint.com>
Date: Mon, 8 Feb 2016 15:25:25 -0800
Subject: [PATCH] Fix fix -- ignore cb if mempool broadcastTx cb is nil

---
 mempool/mempool.go | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/mempool/mempool.go b/mempool/mempool.go
index d4cd86d99..95b91d327 100644
--- a/mempool/mempool.go
+++ b/mempool/mempool.go
@@ -84,10 +84,12 @@ func (mem *Mempool) CheckTx(tx types.Tx, cb func(*tmsp.Response)) (err error) {
 
 	// CACHE
 	if _, exists := mem.cacheMap[string(tx)]; exists {
-		cb(&tmsp.Response{
-			Code: tmsp.CodeType_BadNonce, // TODO or duplicate tx
-			Log:  "Duplicate transaction (ignored)",
-		})
+		if cb != nil {
+			cb(&tmsp.Response{
+				Code: tmsp.CodeType_BadNonce, // TODO or duplicate tx
+				Log:  "Duplicate transaction (ignored)",
+			})
+		}
 		return nil
 	}
 	if mem.cacheList.Len() >= cacheSize {