Calling A Function from the main.ts file to other ts file is not working in Node js

Question

I have a project in Node JS with the following structure:

• ormconfig.js
• package.json
• src
  • main.ts
  • user
    • user.module.ts
    • user.entity.ts
    • user.service.ts (include a function "this.reposiroty.find(...)")
  • mailer
    • mailer.module.ts
    • mailer.service.ts
    • mailer.listener.ts ("the problem is here")

"main.ts" calls a function in "mailer.listener.ts", then "mailer.listener.ts" calls in its turn the function FindAlltoAlert in "user.service.ts", accordingly, an error printed to the console (Error: Cannot read property 'find' of undefined), which is generated when "mailer.listener.ts" calls function FindAlltoAlert in "user.service.ts".

Please advise!