fix: raise exception when type of DocList is object (#1794)

Signed-off-by: punndcoder28 <puneethk.2899@gmail.com>

docarray/array/doc_list/doc_list.py

@@ -16,7 +16,7 @@
 
 from pydantic import parse_obj_as
 from typing_extensions import SupportsIndex
-from typing_inspect import is_union_type
+from typing_inspect import is_union_type, is_typevar
 
 from docarray.array.any_array import AnyDocArray
 from docarray.array.doc_list.io import IOMixinDocList
@@ -337,8 +337,15 @@ def __class_getitem__(cls, item: Union[Type[BaseDoc], TypeVar, str]):
 
         if isinstance(item, type) and safe_issubclass(item, BaseDoc):
             return AnyDocArray.__class_getitem__.__func__(cls, item)  # type: ignore
-        else:
-            return super().__class_getitem__(item)
+        if (
+            isinstance(item, object)
+            and not is_typevar(item)
+            and not isinstance(item, str)
+            and item is not Any
+        ):
+            raise TypeError('Expecting a type, got object instead')
+
+        return super().__class_getitem__(item)
 
     def __repr__(self):
         return AnyDocArray.__repr__(self)  # type: ignore

tests/units/array/test_array.py

@@ -487,3 +487,13 @@ def test_legacy_doc():
     newDoc = LegacyDocument()
     da = DocList[LegacyDocument]([newDoc])
     da.summary()
+
+
+def test_parameterize_list():
+    from docarray import DocList, BaseDoc
+
+    with pytest.raises(TypeError) as excinfo:
+        doc = DocList[BaseDoc()]
+        assert doc is None
+
+    assert str(excinfo.value) == 'Expecting a type, got object instead'