Reassigning nullable in if block

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

After cheking for null in IF block, variable should return not null.

Actual Behaviour

After cheking for null in IF block, variable returns nullable value, so it causes warning

solution: check in two if blocks or use --[[@as not_nullable_type]]

Reproduction steps

---@class Mclass
local var1= {
---@type number?
var2 = nil,
}

---@param number
local function fun1(var2) end

if var1 and var1.var2 then
local var2= var1.var2
fun1(var2) --Cannot assign number? to parameter number.
end

Additional Notes

No response

Log File

No response

使用 Visual Studio Code 擴充功能從 issue 中的 Lua 重現開始，檢查 if 區塊內 nullable 欄位周圍的型別檢查行為。確認回報的警告，並追蹤經過檢查的值指派給區域變數時的型別。完成的標準是保留 narrowing，使得將該變數傳遞給 number 參數時不再回報 nullable 型別警告。