Multiple TypeError crashes: undefined is not an object (R.map and T.match) in result rendering

Description

Claude Code crashes with multiple "undefined is not an object" errors when rendering tool results. Two related issues observed:

1. undefined is not an object (evaluating 'R.map') - in Grep result rendering
2. undefined is not an object (evaluating 'T.match') - in Bash result rendering

Environment

• Claude Code Version: 2.0.72
• OS: macOS (Darwin 25.1.0) - arm64
• Node.js: v25.2.1
• Bun: 1.3.3

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Bug 1: R.map error

Error Message

ERROR  undefined is not an object (evaluating 'R.map')

Stack Trace

- ya_ (/$bunfs/root/claude:1161:1824)
- wbB (/$bunfs/root/claude:2568:3944)
- uq (/$bunfs/root/claude:173:20697)
...

Steps to Reproduce

User asked about FastAPI routing behavior, Claude performed internal Grep search.

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Bug 2: T.match error

Error Message

ERROR  undefined is not an object (evaluating 'T.match')

Stack Trace

/$bunfs/root/claude:2587:12862

Steps to Reproduce

curl -s http://localhost:1907/random-prefix/api/v1/health 2>&1 | head -20

Response was:

{"detail": "Not Found"}

The error occurred when Claude tried to render the Bash tool result.

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Root Cause Analysis

Both errors appear to be missing null checks before calling methods on potentially undefined variables:

1. Bug 1: filenames parameter (R) is undefined when .map() is called
2. Bug 2: Some text parameter (T) is undefined when .match() is called

The rendering functions assume these values always exist, but they can be undefined in certain edge cases.

Suggested Fix

Add defensive null checks:

// Bug 1
let C = (R || []).map((q) => q).join(`\n`);

// Bug 2  
if (!T) return { cleanedStderr: "" };
let R = T.match(pattern);

Additional Context

• Running multiple Claude Code instances simultaneously
• Errors occur intermittently during tool result rendering