Silent error when setting an `undefined` value with `HMSET` inside a transaction

Environment:

• Node.js Version: 16.14.0
• Redis Server Version: 5.0.7
• Node Redis Version: 3.1.2
• Platform: Ubuntu 20.04.3

When setting an undefined value in a hash with HSET or HMSET, an error will result. This is to be expected.

redis.hmset ('test', {a: 'b', c: undefined}, console.log);

Error: node_redis: The HMSET command contains a invalid argument type of "undefined".
Only strings, dates and buffers are accepted. Please update your code to use valid argument types.

When doing the same thing inside a multi block, however, no error will be reported.

var multi = redis.multi ();
multi.hmset ('test', {a: 'b', c: undefined});
multi.exec (function (error) {console.log ('Error: ' + error)})

Error: null

Within the context of a HSET, this wouldn't be an issue because there's a single field to be set. However, because it's an HMSET, the other fields would be expected to be set.

This is particularly problematic because in older versions of node-redis (or perhaps of both node-redis and redis itself) any undefined values in a field would be ignored, while the other ones would still be set. In the examples above, using this older version(s), within the test hash, field a would have been set to b. Anyone relying on the above behavior would silently encounter a scenario where the HMSET operation doesn't happen at all, without any warning. That's actually what happened to me :|

This issue is probably related to #689

In closing, I'd like to thank the original author and the team for writing and maintaining node-redis, which I find to be a spectacular piece of software and a core part of my stack. I've used it heavily for 9+ years and this is the first issue (or perhaps surprise) I have encountered. Thank you.

Start by reproducing the HMSET examples with an undefined value both directly and through multi/exec. Trace the HMSET argument validation and transaction execution paths; done means the invalid argument is no longer silently accepted inside a transaction and the reported behavior is covered by an appropriate test.