Vector types are compatible with array types and empty table types in the new solver, despite being unrelated

[nothing1649]

As of version 0.663, the vector type is compatible with array types and the empty table type. This causes problems where a type error should be reported, but simply doesn't appear. This only occurs in the new solver.

--!strict
local _:{string} = vector.zero --no type error
local _:{} = vector.zero --nothing here either

[hgoldstein]

Gave me a scare! I thought this was related to the work I was doing on bidirectional inference.

Thank you for the report! I think this has been around for a while, feel free to chime in if you think it's a recent regression. It looks like the way we do sub-typing of tables and classes is fuzzy: we only check properties that exist on the table super type ... meaning that empty tables and indexer only tables get a free pass.