[BUG] Claude Desktop crashes with "e.replace is not a function" (error code: 1GY780K) when using Lark MCP tool to read documents

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Claude Desktop crashes and shows the "Claude will return soon" disruption page
(error code: 1GY780K) whenever Claude attempts to respond in a conversation
where the Lark MCP server is configured. The crash occurs during response
rendering — the Lark MCP tool is never actually invoked before the crash happens.

What Should Happen?

Claude Desktop should successfully call the Lark MCP tools and render the
response without crashing.

Error Messages/Logs

From ~/Library/Logs/Claude/claude.ai-web.log:

[BOOTSTRAP] Fatal error boundary triggered {
  "errorMessage": "e.replace is not a function",
  "errorCode": "1GY780K",
  "url": "/local_sessions/local_a8fae05c-e6d2-4230-93e9-cf89e81d2c09",
  "errorStack": "TypeError: e.replace is not a function\n
    at Iet (index-D6CrmkzP.js:25:391377)\n
    at Oet (index-D6CrmkzP.js:25:393718)\n
    at Het (index-D6CrmkzP.js:25:395787)\n
    at Qet (index-D6CrmkzP.js:25:400559)\n
    at index-D6CrmkzP.js:25:582364\n
    at Object.Xi [as useMemo] (vendor-BFBxBwou.js:11:61312)"
}

Steps to Reproduce

1. Add the Lark MCP server to claude_desktop_config.json:

{
"mcpServers": {
"lark-mcp": {
"command": "npx",
"args": ["-y", "@larksuiteoapi/lark-mcp", "mcp", "-a", "<APP_ID>", "-s", "<APP_SECRET>"]
}
}
}

1. Restart Claude Desktop

1. Start a new conversation

1. Send a message asking Claude to read a Lark/Feishu wiki document

(e.g. "Please read this document: https://xxx.feishu.cn/wiki/...")

1. Claude Desktop immediately crashes and displays the

"Claude will return soon" disruption page with error code 1GY780K

Note: The same MCP configuration works correctly in Claude Code CLI.
The crash is 100% reproducible every time.

Claude Model

Sonnet (default)

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude 1.2278.0 (e5213f) 2026-04-13T17:49:21.000Z

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_