Jupyter AI /explain command crashes the app instance

### Product Version

- [ ] Amazon SageMaker Studio Classic
- [x] Amazon SageMaker Studio
- [ ] Issue is not related to SageMaker Studio

### Issue Description

Issuing the `/explain` command in Jupyter AI chat window crashes the Jupyter App window and the entire space making it unresponsive with **502 Bad Gateway** error. To reproduce the issue, have either `Amazon Q` or `AWS Bedrock (custom/provisioned)` option configured, select a portion of your notebook, then issue the `/explain` command in the chat window. The kernels will disconnect and JupyterLab will try to reconnect to the kernels (as evidenced by connection attempts visible in the status bar) but to no avail. The entire JupyterApp window becomes unresponsive, and refreshing the page results in a full-screen white page with a **502 Bad Gateway** error. This happens both in the 2.4+ and 3.0+ versions of the out of the box Studio distribution image.

### Expected Behavior

The `/explain` command should work as described in its documentation without crashing the kernels and the space.

### Observed Behavior

_No response_

### Product Category

JupyterLab

### Feedback Category

Reliability and Stability

### Other Details

_No response_

The report identifies Amazon SageMaker Studio, JupyterLab, and the /explain command, but names no repository files or tests. First reproduce the crash with Amazon Q or AWS Bedrock and a selected notebook portion, then investigate the kernel disconnect and 502 response. Done means /explain completes without disconnecting kernels or making the Studio space unresponsive.

Written by the indexing model from the issue text.