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 扩展从 issue 中的 Lua 复现开始，检查 if 块内 nullable 字段周围的类型检查行为。确认报告的警告，并跟踪经过检查的值赋给局部变量时的类型。完成的标准是保留 narrowing，使得将该变量传递给 number 参数时不再报告 nullable 类型警告。