fix(reactivity): observe instance from subclass of Collection (close …

[tarnishablec]

…#1489)

[jacekkarczmarczyk]

not related?

[tarnishablec]

this is to prevent deno plugin in vscode keep prompting error for no .ts extension in import urls
https://github.com/denoland/vscode_deno

[dsonet]

It would introduce unnecessary impact of the runtime performance just for very rare user cases., even though it's technically correct.
Just like concept vs the real world.
IMO the best way to deal with it is to put this into limitations section.

[aztalbot]

A solution with little to no performance impact for this specific case would be a public function to add constructors to the collectionTypes Set (ex. addCollectionType). @tarnishablec Do you think that would work for your use case? The current solution here slows reactive object creation for all use cases. Extending these collection types is not common, so I don't think it would be surprising to have to tell Vue about your new class.