rrorHandler = function(self) {   return function(err, connection) {     if(self.logger.isDebug()) self.logger.debug(f('pool [%s] errored out [%s] with connection [%s]', this.dead, JSON.stringify(err), JSON.stringify(connection)));     if(!self.dead) {       self.state = DISCONNECTED;       self.dead = true;       self.destroy();       self.emit('