Why Your OpenAI JSON Calls Randomly Fail with "could not parse JSON body" (And How to Fix It)

``You're calling OpenAI from Node.js. 99% of requests work. Then randomly:

BadRequestError: 400 could not parse JSON body

Or:

SyntaxError: Invalid JSON: EOF while parsing an object

Or, if you're using tool calling:

Invalid JSON in tool call arguments

You check your code. Nothing changed. You retry manually — it works. You deploy again. It breaks again.

These errors are NOT your bugs. They're transient artifacts from:

Every one of these is intermittent. So you can't debug it with a stack trace. You just suffer.

People usually do this:

try {
  const res = await client.chat.completions.create({...});
} catch (e) {
  const res = await client.chat.completions.create({...});
}

Problems:

Different errors need different handling:

Doing this manually is ~150 lines of code you'll write badly. Or:

npm install @coder12-z/llm-shield

import { shield } from "@coder12-z/llm-shield";
import OpenAI from "openai";

const client = new OpenAI();

const safeCall = shield(async (prompt) =>
  client.chat.completions.create({
    model: "gpt-4o-mini",
    messages: [{ role: "user", content: prompt }],
    response_format: { type: "json_object" },
  }),
  {
    maxRetries: 3,
    onRetry: ({ attempt, kind }) => console.log(`retry #${attempt} (${kind})`),
  }
);

Three lines of config. Zero dependencies. Works with OpenAI, Anthropic, Gemini, or anything that throws Error objects with status and message.

MIT licensed. Feedback welcome.