[type] assert cannot convert circular structure to json

[marcus-sa]

Test can be found here https://github.com/marcus-sa/ngkit/blob/be76fee58879546d42d3a33ab8afe3a4055a1a7a/packages/core/src/lib/router/process.spec.ts#L78-L84

Error: Uncaught (in promise): TypeError: Converting circular structure to JSON
    --> starting at object with constructor 'RouterStateSnapshot'
    |     property '_root' -> object with constructor 'TreeNode'
    |     property 'value' -> object with constructor 'ActivatedRouteSnapshot'
    --- property '_routerState' closes the circle
TypeError: Converting circular structure to JSON
    --> starting at object with constructor 'RouterStateSnapshot'
    |     property '_root' -> object with constructor 'TreeNode'
    |     property 'value' -> object with constructor 'ActivatedRouteSnapshot'
    --- property '_routerState' closes the circle
    at JSON.stringify (<anonymous>)
    at ValidationErrorItem.toString (/Users/marcus-sa/Git/deepkit/deepkit-framework/packages/type/src/validator.ts:97:40)
    at /Users/marcus-sa/Git/deepkit/deepkit-framework/packages/type/src/validator.ts:112:104
    at Array.map (<anonymous>)
    at new ValidationError (/Users/marcus-sa/Git/deepkit/deepkit-framework/packages/type/src/validator.ts:112:93)
    at Module.assert (/Users/marcus-sa/Git/deepkit/deepkit-framework/packages/type/src/typeguard.ts:47:15)

NB: I just realized that the assertion is bound to fail because it expects an array when the actual value is an object, but that doesn't change the fact that the error above shouldn't occur ^