多Agent模式下其中一个SubAgent的internal错误灰导致后续其它SubAgent的CheckPont保存序列化失败

**Describe the bug**

一个supervisor agent调用SubAgentA, SubAgentA抛出innternalNodeError（比如exceed max iteration），SubAgentA transfer to MainAgent, MainAgent调用SubAgentB，SubAgentB事InterruptableAgent，获取user response后回因为SubAgentA的internal错误导致checkpoint保存gob序列化compose.InternalErr没有注册错误

**Version:**
0.7.30

Start by reproducing the described supervisor/SubAgentA/SubAgentB flow on version 0.7.30, including the internal error and subsequent user response. Trace the checkpoint save and gob serialization path; the work is done when a checkpoint can be saved successfully after the earlier SubAgent error.

Written by the indexing model from the issue text.