Migration Guide and Breaking Changes is not full enough

• 1) Many methods now is not available by old names (with legacyMode also too)

So, only way for now (without modifying thousands of files) is patch client object like this, or remap keys with .toLowerCase():

    client.hgetall = client.hGetAll;
    client.hget = client.hGet;
    client.hset = client.hSet;
    client.hmset = client.hSet;
    client.setex = client.setEx;
    ...

• 2) hSet does not allow objects as second parameter anymore

 client.hSet('key', {a: 1, b:2}, callback); 

< ./node_modules/@node-redis/client/dist/lib/commander.js:72
        yield `$${byteLength.toString()}${DELIMITER}`;
                             ^

TypeError: Cannot read properties of undefined (reading 'toString')
    at encodeCommand (./node_modules/@node-redis/client/dist/lib/commander.js:72:30)
    at encodeCommand.next (<anonymous>)
    at RedisSocket.writeCommand (./node_modules/@node-redis/client/dist/lib/client/socket.js:56:20)
    at Commander._RedisClient_tick (./node_modules/@node-redis/client/dist/lib/client/index.js:415:64)
    at Commander._RedisClient_sendCommand (./node_modules/@node-redis/client/dist/lib/client/index.js:396:82)
    at Commander.sendCommand (./node_modules/@node-redis/client/dist/lib/client/index.js:349:93)
    at Commander.<computed> (./node_modules/@node-redis/client/dist/lib/client/index.js:383:14)

But previously, on 3.x its works:

client.hmset('key', {a: 1, b: 2}, callback); 

< HMSET key a 1 b 2

Functionality hiddenly broken, and no alternative provided.

Current solution is writing a wrap for hmset like this:

client.hmset = (hkey, parms, callback) => {
    client.hSet(hkey, Object.entries(parms).flat(), callback)
}

• 3) Connection errors did not crash process with uncatched errors anymore. Strange thing, but seems like something changed in error policy of this module. I haven't figured it out yet, but when connection is lost, algorithm simply stop on redis commandSending forever.

---

• 4) (Bonus) Types for legacyMode and callbacks is not provided, but in 3.x its does, and for 2.x too: https://www.npmjs.com/package/@types/redis,
  Dirty way for now is patch node_modules/@node-redis/client/dist/lib/client/index.d.ts and add it to WithCommands type

export declare type RedisClientCommandSignatureLegacy<C extends RedisCommand> = (...args: [...options: Parameters<C['transformArguments']>, callback: (e: Error | null, result: RedisCommandReply<C>) => void]) => void

Also, I think that users can additionally import something like LegacyTypesHelper module that will override signatures until legacyMode enabled.

---

• 5) Importing of { RedisClient } from "redis" now is not available anymore.
  Current solution is craft it by yourself: (but it seems like a crutch)

import { createClient } from 'redis'
type RedisClient = ReturnType<typeof createClient>

But I think develops can provide more useful type with generics, but not delete it at all.
Many things, like cache adapters, models or abstract classes require that type. Also, will be useful, if develop may declare that
code expected pure RedisClient or RedisClient with RediJson module.

Anyway it should be described in migration guide.

• 6) Another thing for the migration guide. SCAN args have changed, requiring client.SCAN(cursor, { MATCH: keyPattern, COUNT: pageSize }) pageSize is a Number. It used to take client.SCAN(cursorString, 'MATCH', keyPattern, 'COUNT', pageSize.toString()).

  And the response has changed. Instead of an array of strings [<cursor>, <keys>], it now returns a structure {cursor: <number>, keys: <keys>}. (thx for reporting @jimsnab)

---

Finally, I should say that is very sad example of "how modules shouldn't make breaking updates", especially of so popular module. Feels like a spit into consumers.

Start with the migration guide and the breaking-change points listed in this issue, then inspect the referenced client type declaration at node_modules/@node-redis/client/dist/lib/client/index.d.ts and the command behavior described for hSet and SCAN. Done means the guide documents the reported renamed methods, argument and response changes, connection-error behavior, legacy callback types, and RedisClient import migration.