fix: improve handling of types in option input_type validation (#2893)

* fix: improve handling of Union and tuple types in option input_type validation

* fix: Option type handling for multiple Literals

Updates Option type resolution to return a Union of Literals when all filtered types are Literal, ensuring correct type annotation for command options.

---------

Co-authored-by: Lala Sabathil <[email protected]>

Author: Lumabots

discord/commands/options.py

@@ -372,19 +372,23 @@ def _strip_none_type(input_type):
         if input_type is type(None):
             raise TypeError("Option type cannot be only NoneType")
 
-        if isinstance(input_type, (types.UnionType, tuple)):
-            args = (
-                get_args(input_type)
-                if isinstance(input_type, types.UnionType)
-                else input_type
-            )
+        args = ()
+        if isinstance(input_type, types.UnionType):
+            args = get_args(input_type)
+        elif getattr(input_type, "__origin__", None) is Union:
+            args = get_args(input_type)
+        elif isinstance(input_type, tuple):
+            args = input_type
+
+        if args:
             filtered = tuple(t for t in args if t is not type(None))
             if not filtered:
                 raise TypeError("Option type cannot be only NoneType")
             if len(filtered) == 1:
                 return filtered[0]
-            return filtered
-
+            if all(getattr(t, "__origin__", None) is Literal for t in filtered):
+                return Union[filtered]
+            return Union[filtered]
         return input_type
 
     def to_dict(self) -> dict: