@generic return ignores question mark

How are you using the lua-language-server?

Visual Studio Code Extension (sumneko.lua)

Which OS are you using?

Windows

What is the issue affecting?

Type Checking

Expected Behaviour

Type of y in example below is integer?

Actual Behaviour

Type of y in example below is integer

Reproduction steps

---@generic T
---@param test T
---@return T?
function Func(test)
end

--- @return integer?
function Func2()
end

local x = 0
local y = Func(x)
local z = Func2()

Additional Notes

T | nil works as a workaround.

Log File

No response

Visual Studio Code拡張機能でLuaスニペットを再現し、yとzの推論された型を調べて、T?とT | nilのワークアラウンドを比較します。完了条件は、ジェネリックな@return T?がnilを保持することでyがinteger?になり、一方で既存のFunc2の結果が引き続きinteger?になることです。