Narrowing Types Issue

### 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

```
---@param param1 true | nil
---@param param2 false | nil
local function test(param1, param2)
if param1 == nil and param2 == nil then
local var3 = param1
local var4 = param2
elseif param1 ~= nil and param2 == nil then
local var5 = param1
local var6 = param2
elseif param1 == nil and param2 ~= nil then
local var7 = param1
local var8 = param2
else
local var9 = param1
local var10 = param2
end
end
```

In this function the vars should have the following types:
var3: nil
var4: nil
var5: true
var6: nil
var7: nil
var8: false
var9: true
var10: false

### Actual Behaviour

The actual values are:
var3: nil (correct)
var4: nil (correct)
var5: true (correct)
var6: nil (correct)
var7: nil (correct)
var8: unknown (incorrect)
var9: true | nil (incorrect)
var10: false | nil (incorrect)

### Reproduction steps

1. Copy Code
2. See Issue

### Additional Notes

_No response_

### Log File

_No response_

Start by reproducing the Lua snippet in the Visual Studio Code extension on Windows and trace the type-checking behavior for the final two branches. Done means the inferred types match the report: var8 is false, var9 is true, and var10 is false, with the earlier variables retaining their listed types.

Written by the indexing model from the issue text.