introduce new IncrementalPublisher class

Replicates graphql/graphql-js@d766c8e

Author: Cito

docs/conf.py

@@ -168,7 +168,7 @@
 graphql.execution.Middleware
 graphql.execution.execute.ExperimentalIncrementalExecutionResults
 graphql.execution.execute.StreamArguments
-graphql.execution.incremental_publisher.IncrementalPublisherMixin
+graphql.execution.incremental_publisher.IncrementalPublisher
 graphql.execution.incremental_publisher.StreamItemsRecord
 graphql.execution.incremental_publisher.DeferredFragmentRecord
 graphql.language.lexer.EscapeSequence

src/graphql/error/located_error.py

@@ -13,6 +13,8 @@
 
 __all__ = ["located_error"]
 
+suppress_attribute_error = suppress(AttributeError)
+
 
 def located_error(
     original_error: Exception,
@@ -45,6 +47,6 @@ def located_error(
     except AttributeError:
         positions = None
 
-    with suppress(AttributeError):
+    with suppress_attribute_error:
         nodes = original_error.nodes or nodes  # type: ignore
     return GraphQLError(message, nodes, source, positions, path, original_error)