I'm not sure if this is a bug, because ZRANGESTORE command doesn't allow src to be null, and it would make sense to reply a error when src is null.

@sundb by "null" I mean an empty key (BTW, removing all the members from a sorted set will also reset the key value to null)

@leibale All keys in redis will not be empty(except stream), if empty key will be deleted.
Where did you found that sorted set was empty?

@sundb yea, you're right, an empty sorted set will be deleted, but still: throwing an error in case the src points to null/empty/void/whatever you'll call it, will make this script throw an error

ZADD a 1 a
ZREM a a
ZRANGESTORE b a 0 -1

@leibale I'm not sure I fully understand what you're saying.
The rely (empty array) doesn't mean that b becomes an empty key.
Your modification will cause b to be overwritten even if a does not exist, which should not make sense.

@sundb I feel like my short comments with my broken English will not get this forward.. let me try to explain myself again:

The "normal" behavior of ZRANGESTORE is - it'll override the dest key with a range from the src key, for example:

ZADD src 1 srcMember
(integer) 1
ZADD dest 1 destMember
(integer) 1
ZRANGESTORE dest src 0 -1
(integer) 1
ZSCORE dest srcMember
"1"
ZSCORE dest destMember
(nil)

but, when coping from a not existing src, the reply is (empty array), and the dest key is not being deleted:

ZADD dest 1 destMember
(integer) 1
ZRANGESTORE dest src 0 -1
(empty array)
ZSCORE dest destMember
(integer) 1

The problems with the current implementations are:

1. the command documentation states that the command returns "Integer Reply" - and sometimes it's returning an array.
2. the command normally overrides the dest key, not doing that when the src key does not exist is very not intuitive, and could create strange bugs when working with a set that was deleted after running ZREM.
3. ZDIFFSTORE, ZUNIONSTORE and ZINTERSTORE are all behaving as I suggest we should do here.

@leibale Indeed, after looking at the code of the other commands, your modification is correct.

i see that SINTERSTORE (one of the oldest most mature commands that resembles ZRANGESTORE) returns 0 when the src key is missing, but it does still delete the key. (returning nil is certainly wrong too)
However, when the src key is a wrong type (a string key), it returns an error (WRONGTYPE) and in that case the dest key isn't deleted.

@redis/core-team this is a braking-change fix for a new command we introduced in 6.2.
please approve and state if you feel the fix should be backported to 6.2.

@leibale thank you for reporting and fixing.
i noticed the case of WRONGTYPE wasn't covered, so i added a test for it in this PR (hope i got it right this time)

Should be backported to 6.2.x imo.