Don't complete with error.

Author: benjie

spec/Section 6 -- Execution.md

@@ -306,12 +306,12 @@ MapSourceToResponseEvent(sourceStream, subscription, schema, variableValues):
     sourceValue)}.
   - If internal {error} was raised:
     - Cancel {sourceStream}.
-    - Complete {responseStream} with {error}.
+    - Perform {EmitErrorAndComplete(responseStream, error)}.
   - Otherwise emit {response} on {responseStream}.
 - When {sourceStream} completes normally:
   - Complete {responseStream} normally.
 - When {sourceStream} completes with {error}:
-  - Complete {responseStream} with {error}.
+  - Perform {EmitErrorAndComplete(responseStream, error)}.
 - When {responseStream} is cancelled:
   - Cancel {sourceStream}.
   - Complete {responseStream} normally.
@@ -337,6 +337,13 @@ ExecuteSubscriptionEvent(subscription, schema, variableValues, initialValue):
 Note: The {ExecuteSubscriptionEvent()} algorithm is intentionally similar to
 {ExecuteQuery()} since this is how each event result is produced.
 
+EmitErrorAndComplete(responseStream, error):
+
+- Let {errors} be a list containing {error}.
+- Let {response} be an unordered map containing {errors}.
+- Emit {response} on {responseStream}.
+- Complete {responseStream} normally.
+
 #### Unsubscribe
 
 Unsubscribe cancels the Response Stream when a client no longer wishes to