What causes "Invalid value for --${name}: ${raw}" in chenglou/pretext?

Pass a base-10 integer, e.g. `--step=10`.

chenglou/pretext · error · Error

Invalid value for --${name}: ${raw}

Error message

Invalid value for --${name}: ${raw}

What it means

Thrown by the taxonomy script's `parseNumberFlag` when a required numeric flag is present but not a finite integer. Covers `--port`, `--timeout`, `--start`, `--end`, and `--step`.

Source

Thrown at scripts/corpus-taxonomy.ts:69

type TaxonomyEntry = {
  width: number
  diffPx: number
  category: TaxonomyCategory
  reason: string
  deltaText: string
}

function parseStringFlag(name: string): string | null {
  const prefix = `--${name}=`
  const arg = process.argv.find(value => value.startsWith(prefix))
  return arg === undefined ? null : arg.slice(prefix.length)
}

function parseNumberFlag(name: string, fallback: number): number {
  const raw = parseStringFlag(name)
  if (raw === null) return fallback
  const parsed = Number.parseInt(raw, 10)
  if (!Number.isFinite(parsed)) throw new Error(`Invalid value for --${name}: ${raw}`)
  return parsed
}

function parseOptionalNumberFlag(name: string): number | null {
  const raw = parseStringFlag(name)
  if (raw === null) return null
  const parsed = Number.parseInt(raw, 10)
  if (!Number.isFinite(parsed)) throw new Error(`Invalid value for --${name}: ${raw}`)
  return parsed
}

function parseBrowser(value: string | null): BrowserKind {
  const browser = (value ?? process.env['CORPUS_CHECK_BROWSER'] ?? 'chrome').toLowerCase()
  if (browser !== 'chrome' && browser !== 'safari') {
    throw new Error(`Unsupported browser ${browser}; expected chrome or safari`)
  }
  return browser
}

View on GitHub (pinned to ac49b09b7d)

Solutions

Pass a base-10 integer, e.g. `--step=10`.
Strip unit suffixes; `--timeout` is milliseconds (`--timeout=180000`).
Check for a stray `=` with no value.

Example fix

// before
bun run scripts/corpus-taxonomy.ts --id=ja-kumo-no-ito --step=10px
// after
bun run scripts/corpus-taxonomy.ts --id=ja-kumo-no-ito --step=10

Defensive patterns

Strategy: validation

Validate before calling

for (const name of ['port', 'timeout', 'start', 'end', 'step']) {
  const raw = parseStringFlag(name)
  if (raw !== null && !/^-?\d+$/.test(raw)) {
    console.error(`--${name} must be a base-10 integer, got: ${raw}`)
    process.exit(2)
  }
}

Type guard

const isIntString = (v: string): boolean => /^-?\d+$/.test(v)

Prevention

Pass bare base-10 integers to numeric flags.
Remember --timeout is milliseconds with no suffix.
Avoid empty --flag= tokens.

When it happens

Trigger: `bun run scripts/corpus-taxonomy.ts --id=... --step=abc`, `--port=0x10`, or `--timeout=30s` — parseInt returns NaN.

Common situations: Typo; unit suffix on `--timeout` (milliseconds); hex value; empty `--flag=`.

Related errors

AI-assisted analysis of chenglou/pretext@ac49b09b7d (2026-08-12). Data as JSON: /api/errors/fb7d05c130c76d05. Report an issue: GitHub.