jackwener/OpenCLI · error · ArgumentError

--length must be a positive integer

Error message

--length must be a positive integer

What it means

This ArgumentError comes from `parseSlideDeckLength` and validates the `--length` option of `notebooklm generate-slides`. The value must be a positive integer (or empty/undefined, which defaults to 3); anything else — non-numeric strings, decimals, zero, or negatives — throws.

Source

Thrown at clis/notebooklm/generate-slides.js:52

export function parseSlidesIdFromResult(result, excludedIds = []) {
    const excluded = toExcludedUuidSet(excludedIds);
    if (typeof result === 'string' && ARTIFACT_UUID_RE.test(result) && !excluded.has(result.toLowerCase())) return result;
    const stack = [result];
    while (stack.length) {
        const node = stack.shift();
        if (typeof node === 'string' && ARTIFACT_UUID_RE.test(node) && !excluded.has(node.toLowerCase())) return node;
        if (Array.isArray(node)) for (const child of node) stack.push(child);
        else if (node && typeof node === 'object') for (const v of Object.values(node)) stack.push(v);
    }
    return '';
}

export function parseSlideDeckLength(value) {
    if (value === undefined || value === '') return 3;
    const length = Number(value);
    if (!Number.isInteger(length) || length <= 0) {
        throw new ArgumentError('--length must be a positive integer');
    }
    return length;
}

cli({
    site: NOTEBOOKLM_SITE,
    name: 'generate-slides',
    access: 'write',
    description: 'Trigger a Slide Deck (AI presentation) generation for a NotebookLM notebook, using all of its sources',
    domain: NOTEBOOKLM_DOMAIN,
    strategy: Strategy.COOKIE,
    browser: true,
    navigateBefore: false,
    args: [
        { name: 'notebook', positional: true, required: true, help: 'Notebook id from `notebooklm list` or full notebook URL' },
        { name: 'length', help: 'Slide deck length: 1=Short, 3=Default (default 3)' },
        { name: 'language', help: 'Language code (default en)' },
        { name: 'execute', type: 'boolean', help: 'Actually trigger remote NotebookLM slide deck generation' },

View on GitHub (pinned to 49907e53dc)

Solutions

1. Pass a positive integer, e.g. `--length 5`.
2. Omit `--length` entirely to use the default of 3.
3. Quote the value if your shell mangles it: `--length="5"`.

Example fix

// before
opencli notebooklm generate-slides --notebook id --length 2.5
// after
opencli notebooklm generate-slides --notebook id --length 5

function validateLength(value) {
  if (value === undefined || value === '') return 3;
  const n = Number(value);
  if (!Number.isInteger(n) || n <= 0) throw new Error(`--length must be a positive integer, got ${JSON.stringify(value)}`);
  return n;
}

const isPositiveInt = (v) => Number.isInteger(Number(v)) && Number(v) > 0;

try {
  await generateSlides({ notebookId, length });
} catch (e) {
  if (String(e.message).includes('--length must be a positive integer')) {
    throw new Error(`Bad --length value: ${JSON.stringify(length)}; use a positive integer or omit for default 3`);
  }
  throw e;
}

When it happens

Trigger: Passing `--length 0`, `--length -1`, `--length 2.5`, `--length "three"`, or `--length ""`-adjacent garbage like `--length abc` to generate-slides.

Common situations: Copy-pasted flags with units ('10 slides'), locale decimal commas ('2,5'), or shell quoting issues splitting the value.

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

• ${label} must be a non-negative integer, got ${JSON.stringif
• limit must be a positive integer
• bilibili comment ${label} must be a positive integer
• bilibili comment message cannot be empty
• bilibili unfollow target cannot be empty

AI-assisted analysis of jackwener/OpenCLI@49907e53dc (2026-08-29). Data as JSON: /api/errors/16dff1482900d0d7. Report an issue: GitHub.