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

Start with the Lua reproduction in the issue using the Visual Studio Code extension and inspect the type-checking behavior around the nullable field inside the if block. Confirm the reported warning and trace how the checked value is typed when assigned to the local variable. Done means the narrowing is preserved so passing that variable to the number parameter no longer reports a nullable-type warning.