santifer/career-ops · error · Error

Existing candidates file at ${candidatesPath} is not a JSON

Error message

Existing candidates file at ${candidatesPath} is not a JSON array

What it means

Thrown by appendCandidate() when data/reply-candidates.json parses successfully but the top-level value is not a JSON array (e.g. an object, a string, a number). The contract is an array of candidate objects; a non-array base would break every downstream reader of reply-candidates.json.

Source

Thrown at paste-reply.mjs:123

  };
}

/**
 * Append a candidate to the candidates JSON file, creating the file/array if
 * missing, without disturbing any existing entries. Exported for direct unit
 * testing. Returns the total candidate count after the append.
 */
export function appendCandidate(candidate, candidatesPath = CANDIDATES_PATH) {
  let candidates = [];
  if (fs.existsSync(candidatesPath)) {
    let parsed;
    try {
      parsed = JSON.parse(fs.readFileSync(candidatesPath, 'utf-8'));
    } catch (e) {
      throw new Error(`Could not parse existing candidates file at ${candidatesPath}: ${e.message}`);
    }
    if (!Array.isArray(parsed)) {
      throw new Error(`Existing candidates file at ${candidatesPath} is not a JSON array`);
    }
    candidates = parsed;
  } else {
    fs.mkdirSync(path.dirname(candidatesPath), { recursive: true });
  }
  candidates.push(candidate);
  // Write-then-rename so an interrupted write (crash, signal, disk full)
  // can never leave the real candidates file truncated/corrupted.
  const tmpPath = `${candidatesPath}.tmp`;
  fs.writeFileSync(tmpPath, JSON.stringify(candidates, null, 2), 'utf-8');
  fs.renameSync(tmpPath, candidatesPath);
  return candidates.length;
}

// Collect subject/from/body from stdin via a single readline.Interface and a
// tiny manual state machine driven off its 'line' event.
//
// Earlier drafts chained `rl.question()` calls (one interface per prompt, or

View on GitHub (pinned to 9b17a8ac97)

Solutions

1. Inspect the file's top-level structure and convert it to a plain array of candidate objects.
2. If unsure of the intended contents, back up the file and replace it with an empty array [].
3. Confirm no other writer is serializing a non-array shape.
4. Add a guard in your own writers to always pass arrays to JSON.stringify.

Example fix

// before: top-level object
{ "last": { "company": "Acme" } }
// after: top-level array
[ { "company": "Acme" } ]

import { readFileSync } from 'fs';
function candidatesIsArray(p) {
  try { return Array.isArray(JSON.parse(readFileSync(p, 'utf8'))); }
  catch { return false; }
}

/** Confirms the candidates file's top-level value is the expected array shape. */
function candidatesIsArray(p) {
  try {
    const v = JSON.parse(readFileSync(p, 'utf8'));
    return Array.isArray(v);
  } catch {
    return false;
  }
}

try {
  appendCandidate(c);
} catch (e) {
  if (/is not a JSON array/.test(e.message)) {
    // rewrite file as a valid array (with old contents wrapped if recoverable)
  } else throw e;
}

When it happens

Trigger: The file was overwritten with a single JSON object instead of an array; someone saved `{...}` or a bare string/number as the top-level value; a serialization bug elsewhere wrote the wrong shape.

Common situations: External tool wrote a wrapped object ({candidates:[...]}) instead of the bare array; a test fixture used the wrong shape; an older code path serialized differently.

Related errors

• Could not parse existing candidates file at ${candidatesPath
• payload must include at least one of: cv, articleDigest
• payload.cv requires { section, entry }
• payload.articleDigest requires { entry }
• hackernews: unexpected item response for thread ${threadId}

AI-assisted analysis of santifer/career-ops@9b17a8ac97 (2026-08-13). Data as JSON: /api/errors/5038e568f13ec38b. Report an issue: GitHub.