What causes "index must be a positive integer" in jackwener/OpenCLI?

Pass a whole-number index starting at 1 (1 = most recent post)

index must be a positive integer

Error message

index must be a positive integer

What it means

Inside the browser-evaluated pipeline, the requested post index (after converting to 1-based offset idx = index - 1) is not an integer or is negative. The CLI validates args.index before fetching so that only a valid positive integer selects a post from the user's feed.

Source

Thrown at clis/instagram/comment.js:25

    domain: 'www.instagram.com',
    args: [
        {
            name: 'username',
            required: true,
            positional: true,
            help: 'Username of the post author',
        },
        { name: 'text', required: true, positional: true, help: 'Comment text' },
        { name: 'index', type: 'int', default: 1, help: 'Post index (1 = most recent)' },
    ],
    columns: ['status', 'user', 'text'],
    pipeline: [
        { navigate: 'https://www.instagram.com' },
        { evaluate: `(async () => {
  const username = \${{ args.username | json }};
  const commentText = \${{ args.text | json }};
  const idx = \${{ args.index }} - 1;
  if (!Number.isInteger(idx) || idx < 0) throw new Error('index must be a positive integer');
  const headers = { 'X-IG-App-ID': '936619743392459' };
  const opts = { credentials: 'include', headers };
  async function readInstagramJson(response, label) {
    try {
      return await response.json();
    } catch {
      throw new Error(label + ' returned invalid JSON');
    }
  }
  function getPostFromFeed(feed, label) {
    if (!feed || typeof feed !== 'object' || !Array.isArray(feed.items)) {
      throw new Error(label + ' returned malformed items payload');
    }
    if (idx >= feed.items.length) throw new Error('Post index ' + (idx + 1) + ' not found');
    const post = feed.items[idx];
    const pkRaw = post?.pk ?? post?.id;
    const pk = typeof pkRaw === 'number' ? String(pkRaw) : (typeof pkRaw === 'string' ? pkRaw.trim() : '');
    if (!/^\\d+$/.test(pk)) throw new Error(label + ' returned malformed post row');

View on GitHub (pinned to 49907e53dc)

Solutions

Pass a whole-number index starting at 1 (1 = most recent post)
Strip whitespace and validate with Number.isInteger(Number(index)) && Number(index) >= 1 before invoking
Fix the config/CLI flag so index is a number, not a string with units or formatting

Example fix

// before
instagram comment --username target_user --index 0 --text "nice"
// after
instagram comment --username target_user --index 1 --text "nice"

Defensive patterns

Strategy: validation

Validate before calling

function isValidIndex(n) {
  return Number.isInteger(Number(n)) && Number(n) >= 1;
}
if (!isValidIndex(args.index)) throw new Error('index must be a whole number >= 1');

Type guard

const isPositiveInt = (v) => Number.isInteger(v) && v >= 1;

Try / catch

try {
  await commentOnPost({ username, index, text });
} catch (e) {
  if (/index must be a positive integer/.test(e.message)) {
    console.error('Pass --index as a whole number starting at 1');
  } else throw e;
}

Prevention

Always pass index as a 1-based whole number
Validate CLI flags before invoking
Avoid copying 0-based indices from other tools
Don't pass strings with units or formatting as index

When it happens

Trigger: Calling the comment command with index=0, a negative number, a float (e.g. 2.5), or a non-numeric string that resolves to NaN, making idx not a non-negative integer.

Common situations: Copy-pasting a 0-based index from another tool; passing '1st' or an empty --index flag; a config file where index is a string like "3" that fails templating into the pipeline correctly.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

AI-assisted analysis of jackwener/OpenCLI@49907e53dc (2026-08-29). Data as JSON: /api/errors/a5951fa304472f6a. Report an issue: GitHub.