ZUNIONSTORE returns error for correct request

ie

expected:

     127.0.0.1:6379> ZUNIONSTORE {zset}3 2 {zset}1 {zset}2 WEIGHTS 1 inf
     (integer) 3
     127.0.0.1:6379> ZUNIONSTORE {zset}3 2 {zset}1 {zset}2 weights 1 inf
     (integer) 3

actual:

    127.0.0.1:6379> ZUNIONSTORE {zset}3 2 {zset}1 {zset}2 WEIGHTS 1 inf
    (error) ERR weight value is not a float
    127.0.0.1:6379> ZUNIONSTORE {zset}3 2 {zset}1 {zset}2 weights 1 inf
    (error) ERR syntax error