Hi, I met an question about getLastError, following is code and result, who can tell me why

Code:
$redis = new Redis();
$redis->connect('127.0.0.1', 7100);
$redis->set('mykey', 'value');
$ret = $redis->get('mykey');
var_dump($ret);
$ret = $redis->lrange('mykey', 0, -1);
var_dump($ret);
$ret = $redis->getLastError();
var_dump($ret);

Result:
string(5) "value"
bool(false)
NULL

Execute in redis-cli:
redis 127.0.0.1:7100> get mykey
(nil)
redis 127.0.0.1:7100> set mykey value
OK
redis 127.0.0.1:7100> get mykey
"value"
redis 127.0.0.1:7100> lrange mykey 0 -1
(error) WRONGTYPE Operation against a key holding the wrong kind of value
redis 127.0.0.1:7100>

Redis version: 2.8.9
phpredis version: 2.2.6
PHP version: 5.2.17

Thanks