Type of `self` is not inferred correctly when class is located in a table

I use tables as namespaces, here's a typical module:

```lua
--- @namespace myModule
local ns = {}

--- @class MyClass
ns.MyClass = {}

function ns.MyClass:method()
    -- self is `unknown` here
end

--- @class MyClass2
local MyClass2 = {}

function MyClass2:method()
    -- self is correctly `MyClass2` here
end

return ns
```

Here, self for `ns.MyClass:method` is not inferred correctly.