Why OpenAI JSON Parsing Errors Occur in Node.js and How to Handle Them

Developers using OpenAI's API in Node.js sometimes encounter intermittent JSON parsing errors such as 'could not parse JSON body' or 'EOF while parsing an object,' even when no code changes have been made. These failures stem from three distinct causes: proxy or network corruption mangling request bodies, streaming truncation where JSON is parsed before the stream completes, and model-side malformation of tool call arguments. Because the errors are transient, they cannot be reliably reproduced or debugged through standard stack traces. Different error types require different responses — transient 400 errors need retry with backoff, truncated streams may need higher token limits, and malformed tool arguments require inline sanitization rather than a retry. A lightweight open-source Node.js package called llm-shield has been published to automate this error-handling logic, wrapping existing LLM calls with configurable retry and sanitization behavior across providers including OpenAI, Anthropic, and Gemini.