Cannot validate shape of Errors

[tkelly-mgm]

Describe the bug

When I use Yup to try to check if an Error is an object, it seems to fail, even if all the fields exist.

To Reproduce

const schema = yup.object({
  name: yup.string()
});

const obj = Object.assign(new Error(), {
  name: "Jill"
});

await expect(schema.isValid(obj)).resolves.toBe(true);

Expected behavior

I would expect the given schema to detect the error.

Platform (please complete the following information):

Firefox 124

Additional context

My use case is that I want to build a schema to detect an error thrown by a specific library. The library seems to construct errors with Object.assign(new Error, { ... }), so I can't use instanceof to differentiate from other thrown errors.

[jquense]

What is the failure here, what doesn't work specifically

[tkelly-mgm]

I'm trying to figure out how to get Yup object shape checks to work on an Error object.

I ran a debugger, and it looks like it's failing in a call to isObject:

yup/src/object.ts

Lines 72 to 73 in 5c77e0d

	let isObject = (obj: any): obj is Record<PropertyKey, unknown> =>
	Object.prototype.toString.call(obj) === '[object Object]';

This is saying that new Error() is not an object because Object.prototype.toString.call(new Error()) is [object Error].

Is this intended? Is some other method needed to check the shape of an Error?