Missing diagnostic when passing nil-able fields to pairs/ipairs

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, Diagnostics/Syntax Checking

Expected Behaviour

In the following code, I expect to get param-type mismatch for each of the for loops (with pairs and ipairs) because the variable being iterated can be nil:

---@type string[]?
local x1 = {}

for _ in ipairs(x1) do  -- param-type-mismatch: Cannot assign `string[]?` to parameter `<T:table>
    break
end

---@type table<string, boolean>?
local y1 = {}

for _ in ipairs(y1) do -- param-type-mismatch: Cannot assign `table<string, boolean>?` to parameter `<T:table>
    break
end

---@class Class
---@field x string[]?
---@field y table<string, boolean>?

---@type Class
local x2 = {}

for _ in ipairs(x2.x) do -- Should warn, but it doesn't
    break
end

for _ in pairs(x2.y) do -- Should warn, but it doesn't
    break
end

Actual Behaviour

The param-type-mismatch diagnostic is only shown for the first two loops (direct variables without nesting/fields), but not when using fields (the third and fourth for loops).

Reproduction steps

Copy the code into a Lua file and observe the diagnostics

Additional Notes

No response

Log File

No response

Reproduzieren Sie das Problem, indem Sie das bereitgestellte Lua-Beispiel in eine Lua-Datei kopieren und die Diagnosen für direkte Variablen mit denen für verschachtelte Felder vergleichen. Verfolgen Sie den Pfad der Typprüfung, der Argumente von ipairs und pairs verarbeitet, und überprüfen Sie anschließend, dass nullable Felder dieselbe param-type-mismatch-Diagnose wie direkte Variablen erhalten.