Bedrock streaming: undefined is not an object (evaluating '_.speed')

Bug

When using Claude Code v2.1.86 with Amazon Bedrock as the provider, the error undefined is not an object (evaluating '_.speed') fires repeatedly during streaming (mid-thinking/response), not just at startup. It appears on every streaming chunk.

Environment

• Claude Code version: 2.1.86 (latest)
• Provider: Amazon Bedrock via Teleport proxy (CLAUDE_CODE_USE_BEDROCK=1)
• Model: us.anthropic.claude-opus-4-6-v1
• OS: macOS (Darwin 25.3.0)
• Node.js: with custom --require bootstrap for HTTPS proxy tunneling

Reproduction

1. Configure Bedrock provider (CLAUDE_CODE_USE_BEDROCK=1)
2. Launch Claude Code with a Bedrock model ID
3. Send any prompt — the error appears repeatedly during streaming output

Analysis

The minified code is trying to access .speed on model metadata (_) that is undefined. The Anthropic direct API likely returns speed/performance metadata in the streaming response, but the Bedrock endpoint does not include this field, causing the property access to fail on every chunk.

Current workaround

Filtering stderr: claude --model "$MODEL" 2> >(grep -v '\.speed' >&2)

This suppresses the error messages but doesn't fix the underlying null-safety issue.

Expected behavior

Claude Code should handle missing .speed metadata gracefully when using Bedrock (e.g., optional chaining _.speed → _?.speed).