Fix issue where subscription server data channel closing gives error

[HaraldNordgren]

Handles errors discussed here: #347 (comment)

I have:

• Written a clear PR title and description (above)
• Signed the Khan Academy CLA
• Added tests covering my changes, if applicable
• Included a link to the issue fixed, if applicable
• Included documentation, for new features
• Added an entry to the changelog

[benjaminjkraft]

Seems reasonable to me. It's kinda funny we end up with reflect for this, but it seems fine, and better than adding a bunch of new plumbing to generate a single close call.

I'll wait a couple days in case @matthieu4294967296moineau has anything to add.

[HaraldNordgren]

Yeah, I don't love the reflect part, although it does solves the problem. The reason I still went with it was because I found the same thing in subscriptionsMap.Unsubscribe().

If we really don't want to reflect then a type cast could likely also solve the problem 🤗

[benjaminjkraft]

Ah, I guess it's not the first then!

A cast would be better, but won't work because we don't know the concrete type, right?

[HaraldNordgren]

Ah, right!

[matthieu4294967296moineau]

Ah, I guess it's not the first then!

A cast would be better, but won't work because we don't know the concrete type, right?

yes this is why I used it in a first place to close the channel when unsubscribing

The fix looks good to me, I could test it and it worked fine 👍

[HaraldNordgren]

@benjaminjkraft @matthieu4294967296moineau Great! Thanks for the feedback!

Let's merge? 🚀