santifer/career-ops · error · Error

Could not parse existing candidates file at ${candidatesPath

Error message

Could not parse existing candidates file at ${candidatesPath}: ${e.message}

What it means

Thrown by appendCandidate() in paste-reply.mjs when data/reply-candidates.json exists but JSON.parse fails on its contents. The function is an append-only writer using write-then-rename for crash safety; this guard stops it from appending onto a corrupted base file, which would propagate the corruption.

Source

Thrown at paste-reply.mjs:120

    // Classification is reply-watch.mjs's job, not this script's — leaving
    // signal unset is safe (see file header comment for why).
    signal: null,
  };
}

/**
 * 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

View on GitHub (pinned to 9b17a8ac97)

Solutions

Validate the file with a JSON linter to locate the syntax error, then fix or delete it.
If unrecoverable, back up the corrupt file, delete it, and let appendCandidate recreate a fresh empty array.
Avoid editing reply-candidates.json by hand — it is managed by paste-reply.mjs.
Run `node -e "JSON.parse(require('fs').readFileSync('data/reply-candidates.json','utf8'))"` to confirm the fix.

Example fix

// before: file contains trailing comma -> throws on parse
[
  { ... },
]
// after: valid JSON
[
  { ... }
]

Defensive patterns

Strategy: validation

Validate before calling

import { readFileSync } from 'fs';
function candidatesFileValid(p) {
  try { return Array.isArray(JSON.parse(readFileSync(p, 'utf8'))); }
  catch { return false; }
}
if (!candidatesFileValid(p)) {
  // repair or back up + delete before calling appendCandidate
}

Type guard

null

Try / catch

try {
  appendCandidate(c);
} catch (e) {
  if (/Could not parse/.test(e.message)) {
    // back up corrupt file, delete, retry
  } else throw e;
}

Prevention

Never hand-edit data/reply-candidates.json — let paste-reply.mjs own it.
Back up the file before any external sync tool touches it.
Run a JSON validity check as part of CI/pre-commit.

When it happens

Trigger: The candidates file was partially written/truncated by a previous crash that bypassed the write-then-rename (e.g. an editor or external tool overwrote it directly); manual edit left invalid JSON; disk corruption; an encoding mismatch (BOM, CRLF mangled).

Common situations: A user hand-edited data/reply-candidates.json and broke the syntax; a sync tool (Dropbox/OneDrive) wrote a temp/conflict file over it; a previous version of the code wrote without the tmp+rename atomic pattern.

Related errors

AI-assisted analysis of santifer/career-ops@9b17a8ac97 (2026-08-13). Data as JSON: /api/errors/1b0a6e07aedf2061. Report an issue: GitHub.