feat: let `ctx.session` be undefined for missing session keys

[KnorpelSenf]

The fact that an error is thrown upon property access is really annoying. There is no good way of knowing whether session data exists, so we should change this behaviour.

[KnorpelSenf]

We should probably still throw an error upon assignment to ctx.session

[roziscoding]

I'm guessing the type of ctx.session shouldn't be changed to include undefiend, right?

[KnorpelSenf]

I think so, too. It would be really annoying to work with. Then again ... we either have to accept that the types are wrong (ctx.session is absent but the types say it's not), or we need to retain the existing behaviour of throwing an error when the property is accessed incorrectly. The latter would be justifiable after #6.

[roziscoding]

I get that it could be kind of annoying, but with filtering it'd be easy to get rid of updates missing the session object. We could even export a predicate ourselves, especially after we move sessions to a dedicated plugin

[KnorpelSenf]

What are you envisioning? bot.filter(hasSession)?

[roziscoding]

What are you envisioning? bot.filter(hasSession)?

yep, something like that

[KnorpelSenf]

That feels a bit annoying, don't you think?

[roziscoding]

That feels a bit annoying, don't you think?

not really. the runtime check is already necessary for stuff that depend on the existence of a session key, well just reflect that in the types.

[KnorpelSenf]

I'd just like to find a way to make it unnecessary to check things at runtime. The current implementation doesn't need that and it would feel like a step back to require this from now on

[roziscoding]

The current implementation doesn't need that

I might be missing something here, but I don't really get how this is true. isn't the whole purpose of this PQ to make the check easier? today, if you don't perform that runtime check, you risk getting an error

[KnorpelSenf]

I don't think you're missing something. It's just really annoying to be forced to check for undefined. It's also really annoying that there is not way to check for the presence of the object. In essence, in order to have an ergonomic API, we need ctx.session to be both present and optional at the same time. That's a contradiction. How do we resolve this?

• Compromise on the side of using ctx.session in the common case, and let ctx.session be optional (feat: allow ctx.session to be undefined #2)
• Compromise on the side of checking the the presence of ctx.session in the rare case, and keep on throwing an error (=ignore this issue)
• Have ctx.session be present and still provide a way to check if it will throw, such as one of the following
  • ctx.sessionKey === undefined
  • ctx.hasSession === true
  • hasSession(ctx) === true
  • others