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

Supply a valid integer: --runs=5 or --port=8080.

chenglou/pretext · error · Error

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

Error message

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

What it means

Thrown by parseNumberFlag() in benchmark-check.ts when a --<name>=<value> argument is present on the command line but Number.parseInt(value, 10) is not finite. It is the generic guard for every numeric CLI flag used by the benchmark script (currently --port and --runs). A flag that is absent returns the fallback and does not throw; only a present-but-non-numeric value does.

Source

Thrown at scripts/benchmark-check.ts:84

  'analysisSegments',
  'segments',
  'breakableSegments',
  'width',
  'lineCount',
] as const

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

function median(values: number[]): number {
  const sorted = [...values].sort((a, b) => a - b)
  const mid = Math.floor(sorted.length / 2)
  return sorted.length % 2 === 0 ? (sorted[mid - 1]! + sorted[mid]!) / 2 : sorted[mid]!
}

View on GitHub (pinned to ac49b09b7d)

Solutions

Supply a valid integer: --runs=5 or --port=8080.
If the value is templated, ensure the source variable is set and numeric before interpolation.
Remove the flag to accept its fallback (--port falls back to BENCHMARK_CHECK_PORT env or 0; --runs falls back to BENCHMARK_CHECK_RUNS or 3).
Quote and validate the value before passing it: only forward it when it matches /^[0-9]+$/.

Example fix

# before
bun run scripts/benchmark-check.ts --runs=$RUNS   # RUNS unset -> '--runs='

# after
RUNS="${RUNS:-3}"
bun run scripts/benchmark-check.ts --runs="$RUNS"

Defensive patterns

Strategy: validation

Validate before calling

// Validate numeric flags before the script parses them.
function parseNumberFlag(name: string, fallback: number): number {
  const raw = parseStringFlag(name)
  if (raw === null) return fallback
  if (!/^-?\d+$/.test(raw)) throw new Error(`Invalid value for --${name}: ${raw}`)
  return Number.parseInt(raw, 10)
}

Type guard

function isIntegerFlag(value: string): boolean {
  return /^-?\d+$/.test(value)
}

Try / catch

// Wrap the whole CLI entry so flag errors exit cleanly with a message.
try {
  const runs = parseNumberFlag('runs', 3)
  // ...
} catch (error) {
  console.error(error instanceof Error ? error.message : String(error))
  process.exit(2)
}

Prevention

Quote interpolated variables: `--runs="${RUNS:-3}"` so an unset var becomes the default, not empty.
Validate templated values before invoking the script.
Remember parseInt is lenient with trailing chars ('300px' -> 300); validate with a regex if strictness matters.

When it happens

Trigger: Passing --port=abc, --runs=many, --port= (empty), or any --<numericFlag>=<non-integer-leading> value. Because parseInt stops at the first non-digit, '300px' parses to 300 and does NOT throw; only values with no leading digit run afoul.

Common situations: Typos in the CLI invocation (--runs=thre); copy-pasting a flag value that included a unit or comment; a wrapper script interpolating an unset variable as the value (`--runs=$RUNS` where RUNS is empty).

Related errors

AI-assisted analysis of chenglou/pretext@ac49b09b7d (2026-08-12). Data as JSON: /api/errors/6139a2769008d16b. Report an issue: GitHub.