new api error handling

resolvers/base.py

@@ -1,4 +1,5 @@
-from ariadne import MutationType, QueryType, SubscriptionType, ScalarType
+from ariadne import MutationType, QueryType, SubscriptionType, ScalarType, InterfaceType, UnionType
+
 
 query = QueryType()
 mutation = MutationType()
@@ -12,4 +13,22 @@ def serialize_datetime(value):
 	return value.isoformat()
 
 
-resolvers = [query, mutation, subscription, datetime_scalar]
+class ApiError:
+	def __init__(self, message):
+		self.message = message
+
+error_interface = InterfaceType("ErrorInterface")
+
+@error_interface.type_resolver
+def resolve_search_result_type(obj, *_):
+	if isinstance(obj, ApiError):
+		return "ApiError"
+
+
+sign_in_result = UnionType("SignInResult")
+register_user_result = UnionType("RegisterUserResult")
+
+results = [sign_in_result, register_user_result]
+
+resolvers = [query, mutation, subscription, datetime_scalar, error_interface]
+resolvers.extend(results)