don't pass error as argument when connection is expected

Author: sidorares

lib/pool_connection.js

@@ -13,8 +13,13 @@ function PoolConnection (pool, options) {
   // When a fatal error occurs the connection's protocol ends, which will cause
   // the connection to end as well, thus we only need to watch for the end event
   // and we will be notified of disconnects.
-  this.on('end', this._removeFromPool);
-  this.on('error', this._removeFromPool);
+  var connection = this;
+  this.on('end', function(err) {
+    this._removeFromPool();
+  });
+  this.on('error', function(err) {
+    this._removeFromPool();
+  });
 }
 
 PoolConnection.prototype.release = function () {
@@ -38,11 +43,11 @@ PoolConnection.prototype.end = function () {
 };
 
 PoolConnection.prototype.destroy = function () {
-  this._removeFromPool(this);
+  this._removeFromPool();
   return Connection.prototype.destroy.apply(this, arguments);
 };
 
-PoolConnection.prototype._removeFromPool = function (connection) {
+PoolConnection.prototype._removeFromPool = function () {
   if (!this._pool || this._pool._closed) {
     return;
   }