entry := mustNewEnvSet(ver, baseOpts)
			baseEnvs.Store(key, entry)
			return entry, nil
		})
	} else {
		if entry, ok := baseEnvsWithOption.Load(key); ok {
			return entry.(*EnvSet)
		}
		entry, _, _ = baseEnvsWithOptionSingleflight.Do(key, func() (interface{}, error) {
			entry := mustNewEnvSet(ver, baseOptsWithoutStrictCost)
			baseEnvsWithOption.Store(key, entry)

	if err != nil {
		return nil, err
	}
	baseSet := EnvSet{compatibilityVersion: compatibilityVersion, newExpressions: base, storedExpressions: base}
	return baseSet.Extend(opts...)
}

func mustNewEnvSet(ver *version.Version, opts []VersionedOptions) *EnvSet {
	envSet, err := newEnvSet(ver, opts)
	if err != nil {
		panic(fmt.Sprintf("Default environment misconfigured: %v", err))
	}
	return envSet
}