Merge branch 'master' into chore_update_graphql_core_to_3_3_0

Author: leszekhanusz

gql/transport/aiohttp.py

@@ -325,6 +325,9 @@ async def raise_response_error(resp: aiohttp.ClientResponse, reason: str):
             except Exception:
                 await raise_response_error(resp, "Not a JSON answer")
 
+            if result is None:
+                await raise_response_error(resp, "Not a JSON answer")
+
             if "errors" not in result and "data" not in result:
                 await raise_response_error(resp, 'No "data" or "errors" keys in answer')
 

tests/test_aiohttp.py

@@ -299,6 +299,12 @@ async def handler(request):
             'No "data" or "errors" keys in answer: {"not_data_or_errors": 35}'
         ),
     },
+    {
+        "response": "",
+        "expected_exception": (
+            "Server did not return a GraphQL result: Not a JSON answer: "
+        ),
+    },
 ]