I’ve got a weird bug.

I’m creating a web app with Next.js, and I’m hosting it on Vercel.
I created a class called AdminTopicRepository. When I call new AdminTopicRepository(), the error Maximum call stack size exceeded happenes only in Vercel. Yes, I cannot see this error with npx next start on local environment.
I called only constructor, like this

// ...

export default async function Layout({ children }: { children: ReactNode }) {
    new AdminTopicRepository();

    return (
      // ...
    );
}

And after I removed new AdminTopicRepository statement, no error happened.

Error log from Vercel:

⨯ RangeError: Maximum call stack size exceeded
    at Object.mkdirSync (node:fs:1358:19)
    at n (/var/task/.next/server/chunks/561.js:7:28582)
    at n ...
    at n ...

And the class constains only method, does not have setter or getter.

adminTopicRepository.ts:

import { ITopicRepository } from '@/infrastructure/topic/ITopicRepository';
import { Admin } from '@/firebaseAdmin';
import { firestore } from 'firebase-admin';
import { Timestamp } from 'firebase/firestore';
import { Topic } from '@/domain/topic';
import { ForCreateWithId, ForUpdate } from '@/domain/_utils';
import { logger } from '@/logger';
import { adminTopicConverter } from '@/infrastructure/topic/adminTopicConverter';

export class AdminTopicRepository implements ITopicRepository {
    private readonly colRef = () =>
        Admin.db.collection('topics').withConverter(adminTopicConverter);
    private readonly docRef = (topicId: string) =>
        Admin.db.doc(`topics/${topicId}`).withConverter(adminTopicConverter);

    async create(topic: ForCreateWithId<Topic>): Promise<Topic> {
        try {
            await this.colRef()
                .doc(topic.id)
                .set({
                    ...topic,
                    created_at: firestore.FieldValue.serverTimestamp(),
                    updated_at: firestore.FieldValue.serverTimestamp(),
                });
            logger.log(`Topic created. (${topic.id})`);
            return {
                ...topic,
                id: topic.id,
                created_at: Timestamp.now(),
                updated_at: Timestamp.now(),
            };
        } catch (e) {
            logger.error(e);
            return Promise.reject(e);
        }
    }

    async delete(id: string): Promise<void> {
        try {
            await this.docRef(id).delete();
        } catch (e) {
            logger.error(e);
            return Promise.reject(e);
        }
    }

    async find(id: string): Promise<Topic | undefined> {
        try {
            console.log("Getting topic...")
            const snapshot = await this.docRef(id).get();
            console.log("Got topic.");
            return snapshot.data();
        } catch (e) {
            logger.error(e);
            return Promise.reject(e);
        }
    }

    async findMany(): Promise<Topic[]> {
        try {
            const snapshot = await this.colRef().get();
            return snapshot.docs.map((doc) => doc.data());
        } catch (e) {
            logger.error(e);
            return Promise.reject(e);
        }
    }

    async update(topic: ForUpdate<Topic>): Promise<void> {
        try {
            await this.docRef(topic.id).update({
                ...topic,
                updated_at: firestore.FieldValue.serverTimestamp(),
            });
        } catch (e) {
            logger.error(e);
            return Promise.reject(e);
        }
    }
}

Next.js is literally magic. How can I fix this?

I added empty constructor() method to AdminTopicRepository, but nothing changed.