Function validate

packages/cli/src/ui-prompts.ts:72–83

(value)

    // Clack prints `undefined` on blank submit when placeholder is omitted.
    placeholder: '',
    validate(value) {
      const projectName = value ?? ''

      if (isCurrentDirectoryProjectNameInput(projectName)) {
        return
      }

      const { valid, error } = validateProjectName(projectName)
      if (!valid) {
        return error
      }
    },
  })

  if (isCancel(value)) {