[BUG] TypeError: Cannot read properties of null (reading 'alwaysThinking') on new session launch

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?

• Error: TypeError: Cannot read properties of null (reading 'alwaysThinking') at cli.js:2212
• Trigger: Any new Claude Code session (claude, cd ~ && claude, new terminal tab) — existing sessions unaffected
• Not fixed by: npm install -g @anthropic-ai/claude-code@latest, deleting session .jsonl files, removing effortLevel from

settings

• Platform: macOS (include your sw_vers output)
• Version: include claude --version output
• Settings: ~/.claude/settings.json contains effortLevel: "low", model: "sonnet" — though removing effortLevel did not fix it
• Workaround: Existing sessions continue to work normally; only new session initialization crashes

What Should Happen?

What should happen: Claude Code should launch successfully and present the interactive prompt. The thinking/effort
configuration should initialize with safe defaults if any config value is null or missing, rather than throwing an unhandled
TypeError.

Error Messages/Logs

TypeError: Cannot read properties of null (reading 'alwaysThinking')
    at file:///usr/local/lib/node_modules/@anthropic-ai/claude-code/cli.js:2212:1757
    at Object.useMemo (file:///usr/local/lib/node_modules/@anthropic-ai/claude-code/cli.js:32:25928)
    at J3Q.useMemo (file:///usr/local/lib/node_modules/@anthropic-ai/claude-code/cli.js:8:7000)
    at Tb (file:///usr/local/lib/node_modules/@anthropic-ai/claude-code/cli.js:2212:1735)
    at NC (file:///usr/local/lib/node_modules/@anthropic-ai/claude-code/cli.js:32:19415)
    at Cp (file:///usr/local/lib/node_modules/@anthropic-ai/claude-code/cli.js:34:42814)
    at Z9 (file:///usr/local/lib/node_modules/@anthropic-ai/claude-code/cli.js:34:38355)
    at Eh (file:///usr/local/lib/node_modules/@anthropic-ai/claude-code/cli.js:34:38283)
    at kC (file:///usr/local/lib/node_modules/@anthropic-ai/claude-code/cli.js:34:38137)
    at jH (file:///usr/local/lib/node_modules/@anthropic-ai/claude-code/cli.js:34:35216)

Steps to Reproduce

. Install latest Claude Code (npm install -g @anthropic-ai/claude-code@latest)

1. Open a new terminal tab
2. Run claude in any directory (including cd ~ && claude)
3. Observe crash on launch — never reaches the interactive prompt

Claude Model

Not sure / Multiple models

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.0.9 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_