tweak if statement

Author: yaacovCR

src/execution/execute.ts

@@ -2294,16 +2294,11 @@ async function executeStreamAsyncIteratorItem(
   let item;
   try {
     const iteration = await iterator.next();
-    if (!exeContext.streams.has(streamRecord.streamContext)) {
+    if (!exeContext.streams.has(streamRecord.streamContext) || iteration.done) {
       streamRecord.setIsCompletedIterator();
       return { done: true, value: undefined };
     }
-    const { value, done } = iteration;
-    if (done) {
-      streamRecord.setIsCompletedIterator();
-      return { done, value: undefined };
-    }
-    item = value;
+    item = iteration.value;
   } catch (rawError) {
     handleFieldError(
       rawError,