Fix error message type (#955)

## Changes

Error's Luau type def is `<T>(message: T, level: number): never`, not
`(message: string, level: number): never`. It works as expected by
throwing the passed object instead of a string. I haven't updated the
summary text as this is (mostly) correct.


![image](https://github.com/user-attachments/assets/f93fabdb-d533-4090-aa8f-7a3b79d894a2)


![image](https://github.com/user-attachments/assets/e146f215-7a4e-4c01-a102-af16f24fed68)


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Author: metatablecat

content/en-us/reference/engine/globals/LuaGlobals.yaml

@@ -95,7 +95,7 @@ functions:
       position information to the message.
     parameters:
       - name: message
-        type: string
+        type: Variant
         default:
         summary: |
           The error message to display.