should display error message when opencode binary fails to launch and returns error

http://127.0.0.1:4096/

<img width="861" height="493" alt="Image" src="https://github.com/user-attachments/assets/738a208f-2349-4fb5-830e-a2f74dcb3647" />


should not

<img width="783" height="1491" alt="Image" src="https://github.com/user-attachments/assets/aa89c656-086f-4eb8-a342-a4ba12b01a22" />