Remove typing._UnionGenericAlias for attr checks to reduce import errors.

Author: FayeDel

discord_slash/model.py

@@ -482,14 +482,13 @@ def from_type(cls, t: type):
             return cls.CHANNEL
         if issubclass(t, discord.abc.Role):
             return cls.ROLE
-        # Here's the issue. Typechecking for a **Union** somewhat differs per version (from 3.6.8+)
-
         if hasattr(typing, "_GenericAlias"):  # 3.7 onwards
-            if isinstance(t, typing._UnionGenericAlias):  # noqa
-                return cls.MENTIONABLE  # 3.9+
-            elif t.__origin__ is typing.Union:  # 3.7-3.8
+            # Easier than imports
+            if (
+                t.__origin__ is not None and t.__origin__ is typing.Union
+            ):  # proven in 3.7.8+, 3.8.6+, 3.9+ definitively
                 return cls.MENTIONABLE
-        else:  # py 3.6
+        if not hasattr(typing, "_GenericAlias"):  # py 3.6
             if isinstance(t, typing._Union):  # noqa
                 return cls.MENTIONABLE