Class generics produce unusable and wrong union types

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### How are you using the lua-language-server?

Visual Studio Code Extension (sumneko.lua)

### Which OS are you using?

MacOS, Windows

### What is the issue affecting?

Completion

### Expected Behaviour

Methods `Peek,Push,Pop` have proper type hints

### Actual Behaviour

While types of `a, b, c` are correct the
type hints of methods are unusable with unnecessary union types.

**If `Push` is removed from superclass, then type hints go to normal without unions but still with `` in many places**

```lua
local _lua_setmetatable = setmetatable

Stack = {}

--- @generic T
--- @class Stack : {
--- Pop: (fun(self: Stack): T),
--- Peek: (fun(self: Stack): T),
--- Push: (fun(self: Stack, value: T): Stack),
--- }
--- @field protected _stack any[]
--- @field protected _count integer
Stack.__index = {}

--- Creates a new, empty stack.
--- @generic T
--- @return Stack
function Stack.New()
local this = {
_stack = {},
_count = 0,
}

return _lua_setmetatable(this, Stack)
end

local st = Stack.New() --[[@as Stack<{ num: integer }>]]

local a = st:Peek()
local b = st:Pop()
local c = st:Push({})
```

### Reproduction steps

Analyze specified code in VSCode with luals installed

### Additional Notes

_No response_

### Log File

_No response_

Reproduisez le problème en analysant l’extrait Lua dans VS Code avec lua-language-server installé, en vous concentrant sur les suggestions de complétion pour Stack.New et les méthodes Peek, Pop et Push. Comparez les types inférés de a, b et c avec les suggestions de méthodes attendues sans types union ; le travail est terminé lorsque les méthodes n’affichent plus de types union inutilisables ou superflus, ni d’espaces réservés génériques parasites.

Rédigé par le modèle d'indexation à partir du texte de l'issue.