src/vs/platform/theme/common/colorRegistry.ts/migrateColorDefaults
function migrateColorDefaults(o: any): null | ColorDefaults {
	if (o === null) {
		return o;
	}
	if (typeof o.hcLight === 'undefined') {
		if (o.hcDark === null || typeof o.hcDark === 'string') {
			o.hcLight = o.hcDark;
		} else {
			o.hcLight = o.light;
		}
	}
	return o as ColorDefaults;
}