Fixed original_error.extensions overriding extensions argument

Replicates graphql/graphql-js@188122b

Author: Cito

README.md

@@ -12,7 +12,7 @@ a query language for APIs created by Facebook.
 [![Python 3 Status](https://pyup.io/repos/github/graphql-python/graphql-core/python-3-shield.svg)](https://pyup.io/repos/github/graphql-python/graphql-core/)
 [![Code Style](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/ambv/black)
 
-The current version 3.1.6 of GraphQL-core is up-to-date with GraphQL.js version 15.7.1.
+The current version 3.1.6 of GraphQL-core is up-to-date with GraphQL.js version 15.7.2.
 
 An extensive test suite with over 2200 unit tests and 100% coverage comprises a
 replication of the complete test suite of GraphQL.js, making sure this port is

src/graphql/error/graphql_error.py

@@ -120,12 +120,10 @@ def __init__(
                 self.__cause__ = original_error.__cause__
             elif original_error.__context__:
                 self.__context__ = original_error.__context__
-            if not extensions:
-                try:
-                    # noinspection PyUnresolvedReferences
-                    extensions = original_error.extensions  # type: ignore
-                except AttributeError:
-                    pass
+            if extensions is None:
+                original_extensions = getattr(original_error, "extensions", None)
+                if isinstance(original_extensions, dict):
+                    extensions = original_extensions
         self.extensions = extensions or {}
         if not self.__traceback__:
             self.__traceback__ = exc_info()[2]

src/graphql/version.py

@@ -6,7 +6,7 @@
 
 version = "3.1.6"
 
-version_js = "15.7.1"
+version_js = "15.7.2"
 
 
 _re_version = re.compile(r"(\d+)\.(\d+)\.(\d+)(\D*)(\d*)")

tests/error/test_graphql_error.py

@@ -129,6 +129,29 @@ def converts_source_and_positions_to_locations():
         assert e.positions == [6]
         assert e.locations == [(2, 5)]
 
+    def defaults_to_original_error_extension_only_if_arg_is_not_passed():
+        original_extensions = {"original": "extensions"}
+        original_error = GraphQLError("original", extensions=original_extensions)
+        inherited_error = GraphQLError("InheritedError", original_error=original_error)
+        assert inherited_error.message == "InheritedError"
+        assert inherited_error.original_error is original_error
+        assert inherited_error.extensions is original_extensions
+
+        own_extensions = {"own": "extensions"}
+        own_error = GraphQLError(
+            "OwnError", original_error=original_error, extensions=own_extensions
+        )
+        assert own_error.message == "OwnError"
+        assert own_error.original_error is original_error
+        assert own_error.extensions is own_extensions
+
+        own_empty_error = GraphQLError(
+            "OwnEmptyError", original_error=original_error, extensions={}
+        )
+        assert own_empty_error.message == "OwnEmptyError"
+        assert own_empty_error.original_error is original_error
+        assert own_empty_error.extensions == {}
+
     def serializes_to_include_all_standard_fields():
         e_short = GraphQLError("msg")
         assert str(e_short) == "msg"