Fix agent_completion bug (#4329)

### What problem does this PR solve?

Fix agent_completion bug  #4320

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

---------

Co-authored-by: liuhua <10215101452@stu.ecun.edu.cn>
Co-authored-by: Kevin Hu <kevinhu.sh@gmail.com>

api/apps/sdk/session.py

@@ -35,6 +35,7 @@ from api.utils.api_utils import get_result, token_required
 from api.db.services.llm_service import LLMBundle
 
 
+
 @manager.route('/chats/<chat_id>/sessions', methods=['POST'])  # noqa: F821
 @token_required
 def create(tenant_id, chat_id):
@@ -92,6 +93,9 @@ def create_agent_session(tenant_id, agent_id):
                 else:
                     if "value" in ele:
                         ele.pop("value")
+    else:
+        for ans in canvas.run(stream=False):
+            pass
     cvs.dsl = json.loads(str(canvas))
     conv = {
         "id": get_uuid(),