Fix issue #13084 (#13088)

When match_expressions contains coroutine objects (from GraphRAG's
Dealer.get_vector()), the code cannot identify this type because it only
checks for MatchTextExpr, MatchDenseExpr, or FusionExpr.

As a result:

score_func remains initialized as an empty string ""
This empty string is appended to the output list
The output list is passed to Infinity SDK's table_instance.output()
method
Infinity's SQL parser (via sqlglot) fails to parse the empty string,
throwing a ParseError

api/db/services/canvas_service.py

@@ -203,7 +203,7 @@ async def completion(tenant_id, agent_id, session_id=None, **kwargs):
             conv.message = []
         if not isinstance(conv.dsl, str):
             conv.dsl = json.dumps(conv.dsl, ensure_ascii=False)
-        canvas = Canvas(conv.dsl, tenant_id, agent_id, custom_header=custom_header)
+        canvas = Canvas(conv.dsl, tenant_id, agent_id, canvas_id=agent_id, custom_header=custom_header)
     else:
         e, cvs = UserCanvasService.get_by_id(agent_id)
         assert e, "Agent not found."