fix(jsonschema): guard against empty items list in create_array_type

src/marvin/utilities/jsonschema.py

@@ -215,10 +215,13 @@ def create_array_type(
     if isinstance(items, list):
         # Handle positional item schemas
         item_types = [schema_to_type(s, schemas) for s in items]
-        from typing import Union
+        if not item_types:
+            base = list[Any]
+        else:
+            from typing import Union
 
-        combined = Union[tuple(item_types)]
-        base = list[combined]
+            combined = Union[tuple(item_types)] if len(item_types) > 1 else item_types[0]
+            base = list[combined]
     else:
         # Handle single item schema
         item_type = schema_to_type(items, schemas)

tests/basic/utilities/test_jsonschema.py

@@ -281,6 +281,11 @@ def test_unique_items_converts_duplicates(self, unique_items_array):
         result = validator.validate_python(["a", "a", "b"])
         assert result == {"a", "b"}
 
+    def test_empty_items_list_does_not_crash(self):
+        # items=[] (empty tuple schema) must not raise TypeError from Union[()]
+        result = jsonschema_to_type({"type": "array", "items": []})
+        assert TypeAdapter(result).validate_python([1, "x", None]) == [1, "x", None]
+
 
 class TestObjectTypes:
     """Test suite for object validation."""