chenglou/pretext · error · Error

Unsupported browser ${browser}

Error message

Unsupported browser ${browser}

What it means

parseBrowsers() in letter-spacing-check.ts validates each `--browser=` entry against {chrome, safari, firefox} and throws on any other name. It is the same input-validation guard used across the oracle check scripts.

Source

Thrown at scripts/letter-spacing-check.ts:117

  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 parseBrowsers(value: string | null): AutomationBrowserKind[] {
  const raw = (value ?? 'chrome,safari').trim()
  if (raw.length === 0) return ['chrome', 'safari']

  const browsers = raw
    .split(',')
    .map(part => part.trim().toLowerCase())
    .filter(Boolean)

  for (const browser of browsers) {
    if (browser !== 'chrome' && browser !== 'safari' && browser !== 'firefox') {
      throw new Error(`Unsupported browser ${browser}`)
    }
  }

  return browsers as AutomationBrowserKind[]
}

const requestedPort = parseNumberFlag('port', 0)
const browsers = parseBrowsers(parseStringFlag('browser'))
const timeoutMs = parseNumberFlag('timeout', 60_000)
const output = parseStringFlag('output')

function materializeCase(testCase: LetterSpacingOracleCase): OracleSnapshot['cases'][number] & { text: string } {
  const dir = testCase.dir ?? 'ltr'
  return {
    label: testCase.label,
    text: testCase.text,
    width: testCase.width,
    font: testCase.font,

View on GitHub (pinned to ac49b09b7d)

Solutions

1. Use only chrome, safari, or firefox (case-insensitive), e.g. `--browser=chrome,safari`.
2. Omit `--browser` to get the default chrome,safari.

Example fix

# before
bun run letter-spacing-check -- --browser=edge

# after
bun run letter-spacing-check -- --browser=chrome

const SUPPORTED = new Set(['chrome', 'safari', 'firefox'])
function parseBrowsers(value: string | null): ('chrome' | 'safari' | 'firefox')[] {
  const parts = (value ?? 'chrome,safari').split(',').map(p => p.trim().toLowerCase()).filter(Boolean)
  const bad = parts.filter(p => !SUPPORTED.has(p))
  if (bad.length) {
    console.error(`Unsupported browser(s): ${bad.join(', ')}. Supported: chrome, safari, firefox`)
    process.exit(2)
  }
  return parts as ('chrome' | 'safari' | 'firefox')[]
}

const isSupportedBrowser = (v: string): v is 'chrome' | 'safari' | 'firefox' =>
  v === 'chrome' || v === 'safari' || v === 'firefox'

When it happens

Trigger: Passing `--browser=edge`, `--browser=chromium`, or any token outside the accepted trio.

Common situations: Assuming a Chromium-family alias is supported, or pasting a browser list from a different tool.

Related errors

• Unsupported browser ${browser}
• Unsupported browser ${browser}
• Invalid value for --${name}: ${raw}
• Unsupported browser ${browser}; expected chrome or safari
• --step must be > 0

AI-assisted analysis of chenglou/pretext@ac49b09b7d (2026-08-12). Data as JSON: /api/errors/b00a105ac979d644. Report an issue: GitHub.