How to use this in nestjs decorator

I want to set the file limit on upload using

new MaxFileSizeValidator({ maxSize: this.configService.get<number>('uploadLimit') }),

and I receive configService on controller

  constructor(private readonly configService: ConfigService) {}

The problem that I have currently is that I get an error on

this.configService.get<number>('uploadLimit')

Saying that Object is possibly 'undefined'. I found this solution, but is it somehow possible to fix it without implementing custom interceptor or anything complex?