Improve coverage in graphql module

Don't wrap unexpected errors as GraphQLErrors.

Author: Cito

src/graphql/graphql.py

@@ -153,9 +153,6 @@ def graphql_impl(
         document = parse(source)
     except GraphQLError as error:
         return ExecutionResult(data=None, errors=[error])
-    except Exception as error:
-        error = GraphQLError(str(error), original_error=error)
-        return ExecutionResult(data=None, errors=[error])
 
     # Validate
     from .validation import validate

tests/execution/test_sync.py

@@ -92,6 +92,13 @@ def does_not_return_a_promise_for_validation_errors():
                 ],
             )
 
+        def raises_a_type_error_when_no_query_is_passed():
+            with raises(TypeError) as exc_info:
+                # noinspection PyTypeChecker
+                assert graphql_sync(schema, None)  # type: ignore
+            msg = str(exc_info.value)
+            assert msg == "Must provide Source. Received: None."
+
         def does_not_return_a_promise_for_sync_execution():
             doc = "query Example { syncField }"
             assert graphql_sync(schema, doc, "rootValue") == (