@upstash/context7-mcp/dist/lib/mcp-body-error-handler.js

MCP server for Context7

// Error boundary for the MCP router's JSON body parser. express.json() reports
// a body it will not accept via next(err); left unhandled, Express answers with
// an HTML stack trace naming dependency versions and absolute paths.
export const mcpBodyErrorHandler = (err, req, res, next) => {
    const { status, type } = err;
    // body-parser tags every rejection with a 4xx; anything else is not a body
    // problem. Once a response has started, only Express can wind it down.
    if (typeof status !== "number" || status < 400 || status >= 500 || res.headersSent) {
        return next(err);
    }
    // Method, path and size only: the body is the rejected input, and the
    // headers carry the API key.
    console.error(`Rejected request body (${status}, ${String(type ?? "unknown")}): ${req.method} ${req.baseUrl}${req.path} bytes=${req.headers["content-length"] ?? "unknown"}`);
    // Fixed messages: body-parser's own quote offsets into the body.
    const parseFailure = err instanceof SyntaxError && type === "entity.parse.failed";
    res.status(status).json({
        jsonrpc: "2.0",
        error: parseFailure
            ? { code: -32700, message: "Parse error" }
            : { code: -32600, message: "Invalid Request" },
        id: null,
    });
};