message: FileLog should add newlines, async end function
diff: @@ -12,8 +12,10 @@ export class FileLog extends Log {
  this._createWriteStream();
  }
  - public end(): void {
  - this._logFileStream.end();
  + public async end(): Promise<void> {
  + return new Promise((resolve) => {
  + this._logFileStream.end(resolve);
  + });
  }
  public log(message: string, level: LogLevel): void {
  @@ -38,7 +40,7 @@ export class FileLog extends Log {
  break;
  }
  - this._logFileStream.write(prefix + message);
  + this._logFileStream.write(prefix + message + "\n");
  }
  private _createWriteStream() {
  