jackwener/OpenCLI · error · CommandExecutionError

coingecko derivatives returned malformed JSON: ${err?.messag

Error message

coingecko derivatives returned malformed JSON: ${err?.message ?? err}

What it means

The coingecko derivatives command wraps the response body parse of GET https://api.coingecko.com/api/v3/derivatives in a try/catch. When resp.json() rejects (body is not valid JSON), it rethrows a CommandExecutionError with the underlying parse message. The library throws this because the HTTP request itself succeeded (status was ok), but the payload could not be decoded.

Source

Thrown at clis/coingecko/derivatives.js:57

        }
        catch (err) {
            throw new CommandExecutionError(`coingecko derivatives request failed: ${err?.message ?? err}`);
        }
        if (resp.status === 429) {
            throw new CommandExecutionError(
                'coingecko derivatives returned HTTP 429 (rate limited)',
                'Free tier allows ~30 calls/min. Wait and retry.',
            );
        }
        if (!resp.ok) {
            throw new CommandExecutionError(`coingecko derivatives returned HTTP ${resp.status}`);
        }
        let data;
        try {
            data = await resp.json();
        }
        catch (err) {
            throw new CommandExecutionError(`coingecko derivatives returned malformed JSON: ${err?.message ?? err}`);
        }
        if (!Array.isArray(data) || !data.length) {
            throw new EmptyResultError('coingecko derivatives', 'CoinGecko returned no derivative tickers.');
        }
        let rows = data;
        if (filter) {
            rows = data.filter((d) => String(d.symbol ?? '').toUpperCase().includes(filter)
                || String(d.index_id ?? '').toUpperCase().includes(filter));
            if (!rows.length) {
                throw new EmptyResultError('coingecko derivatives', `No derivative tickers matched symbol="${filter}".`);
            }
        }
        return rows.slice(0, limit).map((d, i) => ({
            rank: i + 1,
            market: String(d.market ?? ''),
            symbol: String(d.symbol ?? ''),
            indexId: String(d.index_id ?? ''),
            contractType: String(d.contract_type ?? ''),

View on GitHub (pinned to 49907e53dc)

Solutions

Retry the command after a short wait — transient CDN/proxy hiccups often resolve on their own.
Check the raw response with curl -s https://api.coingecko.com/api/v3/derivatives | head -c 200 to see what body is actually returned.
Disable or bypass intercepting proxies/VPNs (check HTTP(S)_PROXY env vars) that may inject HTML pages.
Reduce request frequency to avoid Cloudflare bot challenges; consider a CoinGecko Pro API key.
Verify network/DNS allows reaching api.coingecko.com directly.

Example fix

// before — caller assumes success means JSON
const data = await runCli(['coingecko', 'derivatives']);
// after
try {
  const data = await runCli(['coingecko', 'derivatives']);
} catch (err) {
  if (String(err.message).includes('malformed JSON')) {
    await sleep(1000); // transient HTML/Cloudflare page — retry
    return retryDerivatives();
  }
  throw err;
}

Defensive patterns

Strategy: try-catch

Validate before calling

const resp = await fetch('https://api.coingecko.com/api/v3/derivatives');
const text = await resp.text();
if (!resp.ok) throw new Error(`HTTP ${resp.status}`);
try { JSON.parse(text); } catch { console.warn('Non-JSON body, likely HTML challenge/proxy page'); }

Type guard

function isDerivativeArray(v) {
  return Array.isArray(v) && v.every((d) => d != null && typeof d === 'object' && 'symbol' in d);
}

Try / catch

try {
  const rows = await runCli(['coingecko', 'derivatives']);
} catch (err) {
  if (String(err.message).includes('malformed JSON')) {
    return retryWithBackoff(() => runCli(['coingecko', 'derivatives']), 3);
  }
  throw err;
}

Prevention

Retry with backoff on malformed JSON — usually a transient HTML/CDN page.
Bypass suspicious proxies/VPNs; check HTTP(S)_PROXY env vars.
Keep request rate low to avoid Cloudflare bot challenges.
Inspect the raw body (curl) when it recurs to identify the interceptor.

When it happens

Trigger: CoinGecko returns HTTP 200 with a non-JSON body — e.g. an HTML Cloudflare challenge/interstitial page, a proxy/captive-portal interception page, a truncated or empty response body, or a maintenance error page served with a 2xx status.

Common situations: Corporate proxies or VPNs injecting an HTML block page; CoinGecko serving a Cloudflare 'checking your browser' page to the CLI's User-Agent; network middleboxes truncating the response mid-stream; CDN outage returning garbage.

Understand the failure class

Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

AI-assisted analysis of jackwener/OpenCLI@49907e53dc (2026-08-29). Data as JSON: /api/errors/22d14df7d4163a01. Report an issue: GitHub.