[BUG] undefined is not an object (evaluating '$.speed')" on direct Anthropic API (not Bedrock)

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?

### Bug Description

Getting undefined is not an object (evaluating '$.speed') intermittently when using
Claude Code with the direct Anthropic API (not Bedrock, not Vertex). This appears to be
the same root cause as #40189, but that issue is Bedrock-specific — this confirms the
bug also affects the standard Anthropic API provider.

### Environment

• Claude Code version: 2.1.87
• Provider: Anthropic API (direct, no Bedrock/Vertex)
• OS: Ubuntu Linux (6.14.0-37-generic)
• Model: claude-opus-4-6

Related

• #40189 (same error, but Bedrock-specific)

What Should Happen?

The client should use optional chaining (?.speed) or a null check when accessing
the speed field from API usage metadata, as it can be null.

Error Messages/Logs

Steps to Reproduce

The error occurs intermittently — not on every request. In a single day (2026-03-29),
it appeared 8 times across 5 separate sessions. All occurrences are logged as
isApiErrorMessage: true with model: "<synthetic>", indicating a client-side
parsing failure rather than an actual API error.

Claude Model

Not sure / Multiple models

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.87

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other

Additional Information

### Relevant session log data

```json
{
"message": {
"model": "<synthetic>",
"usage": { "speed": null },
"content": [{ "type": "text", "text": "undefined is not an object (evaluating '$.speed')" }]
},
"isApiErrorMessage": true,
"version": "2.1.87"
}