Merge pull request #36 from cmgustavo/bug/01-block-0

Fix #454: when getting pool information of block 0

Ping:
https://github.com/bitpay/insight/issues/454

lib/BlockDb.js

@@ -166,12 +166,15 @@ BlockDb.prototype.getPoolInfo = function(tx, cb) {
   tDb._getInfo(tx, function(e, a) {
     if (e) return cb(false);
 
-    if (a.isCoinBase) {
+    if (a && a.isCoinBase) {
       var coinbaseHexBuffer = new Buffer(a.vin[0].coinbase, 'hex');
       var aa = self.poolMatch.match(coinbaseHexBuffer);
       
       return cb(aa);
     }
+    else {
+      return cb();
+    }
   });
 };