Bug: json-bigint-patch causes CASL ability.can() to fail with BigInt conditions

[guyhirsch]

Describe the bug
When importing json-bigint-patch, the ability check in CASL fails to correctly match conditions using BigInt. Specifically, ability.can() incorrectly returns false when it should return true.

To Reproduce
Steps to reproduce the behavior:

1. Ability configuration:

import 'json-bigint-patch';
import { createMongoAbility, subject } from '@casl/ability';

class Article {
  id: bigint;
}

type Actions = 'all';
type Subjects = Article | typeof Article | 'Article';

const ability = createMongoAbility<[Actions, Subjects]>([
  {
    action: 'all',
    subject: 'Article',
    conditions: { id: 5n },
  },
  {
    action: 'all',
    subject: 'Article',
    conditions: { id: 1n },
  },
]);

const article = new Article();
article.id = 1n;

console.log(ability.can('all', subject('Article', article))); // returns false, but it should return true

2. How abilities are checked:
   Using ability.can() with a condition that should match, but it fails when json-bigint-patch is imported.

Expected behavior
When json-bigint-patch is imported, ability.can() should return true for matching conditions, just as it does without the import.

CASL Version

@casl/ability - v6.7.3

Environment:

1. Node.js: v22.12.0
2. TypeScript: v5.7.2
3. json-bigint-patch: v0.0.8

[stalniy]

json-bigint-patch adds custom toJSON method. Ucsst expects toJSON to return primitive value, but in that patch lib it returns non primitive. I think it actually returns BigInt objectified instance. I’ll double check tomorrow