Postgres TypeError: Converting circular structure to JSON

Issue Description

So I am using postgresql with typeorm and nestjs and I have a user entity. When I run .findOne({username }) it works fine, but doing .find({}) to get all simply gives this error:

TypeError: Converting circular structure to JSON
    --> starting at object with constructor 'Socket'
    |     property 'parser' -> object with constructor 'HTTPParser'       
    --- property 'socket' closes the circle
    at JSON.stringify (<anonymous>)
    at SelectQueryBuilder.<anonymous> (C:\Users\thebo\Documents\ProxyByrd\packages\backend\node_modules\.pnpm\typeorm@0.2.28\node_modules\typeorm\query-builder\SelectQueryBuilder.js:1553:67)

Expected Behavior

The following code should return the list of users to the backend:

    async findAll(): Promise<User[]> {
        return await this.usersRepository.find({ take: 5 });
    }

Actual Behavior

It errors with circular socket structure error:

TypeError: Converting circular structure to JSON
    --> starting at object with constructor 'Socket'
    |     property 'parser' -> object with constructor 'HTTPParser'       
    --- property 'socket' closes the circle
    at JSON.stringify (<anonymous>)
    at SelectQueryBuilder.<anonymous> (C:\Users\thebo\Documents\ProxyByrd\packages\backend\node_modules\.pnpm\typeorm@0.2.28\node_modules\typeorm\query-builder\SelectQueryBuilder.js:1553:67)

Steps to Reproduce

1. Use nestjs and typeorm
2. Try to call .find({}) on an injected repository in a service.

My Environment

Dependency	Version
Operating System	Windows 10
Node.js version	14.0.0
Typescript version	4.0.5
TypeORM version	0.2.28

Relevant Database Driver(s)

• aurora-data-api
• aurora-data-api-pg
• better-sqlite3
• cockroachdb
• cordova
• expo
• mongodb
• mysql
• nativescript
• oracle
• [x ] postgres
• react-native
• sap
• sqlite
• sqlite-abstract
• sqljs
• sqlserver

Are you willing to resolve this issue by submitting a Pull Request?

• Yes, I have the time, and I know how to start.
• Yes, I have the time, but I don’t know how to start. I would need guidance.
• No, I don’t have the time, although I believe I could do it if I had the time…
• No, I don’t have the time and I wouldn’t even know how to start.

[Cleatuer]

@ErolPeel When saving a One-to-Many relation in TypeORM you need to be careful to only reference one side of the relation. For example when you want to save a PartyEntity with a PartyContactEntity, do it like this:

const partyContactEntity: PartyContactEntity = new PartyContactEntity()
partyContactEntity.contactMedium = savedPostalContactEntity.contactMedium
// important: do not set the partyContactEntity.party here as this will result in the 
// "TypeError: Converting circular structure to JSON" error when saving the contact with the party

const partyEntity: PartyEntity = new PartyEntity( ... )
partyEntity.contacts = [partyContactEntity]

manager.save(partyEntity)

[ghost]

It happens in TypeORM 0.2.22 and 0.2.18 as well. I guess, there is some modelling error on my side?