Using a union of string literals as a table key doesn't force use of the keys

How are you using the lua-language-server?

NeoVim

Which OS are you using?

Linux

What is the issue affecting?

Type Checking

Expected Behaviour

---@alias SomeUnion
--- | 'a'
--- | 'b'

---@type table<SomeUnion, number>
local a

should work roughly like

---@class (exact) SomeUnion
---@field a number
---@field b number
local a

Actual Behaviour

Reproduction steps

---@alias SomeUnion
--- | 'a'
--- | 'b'

---@type table<SomeUnion, number>
local a = {
  c = "should be invalid"
}

Additional Notes

No response

Log File

No response

首先复现 issue 中报告的类型检查示例，并跟踪 language server 对类型为字符串字面量联合的表键的处理。完成的标准是：复现中的 c 键被报告为无效，而 a 和 b 键仍保持有效。