src/vs/platform/log/browser/log.ts/logLevelToString
function logLevelToString(level: LogLevel): string {
	switch (level) {
		case LogLevel.Trace: return 'trace';
		case LogLevel.Debug: return 'debug';
		case LogLevel.Info: return 'info';
		case LogLevel.Warning: return 'warn';
		case LogLevel.Error: return 'error';
		case LogLevel.Critical: return 'error';
	}
	return 'info';
}