validateError

Checks whether a value is an Error object. This helper uses isError internally.

Accepts all native Error types (Error, TypeError, RangeError, etc.) and custom subclasses. Never throws and never mutates input.

Signature

function validateError(value: unknown, field: string): ValidationResult<Error>

Parameters

Name	Data type	Description
value	unknown	The value to validate.
field	string	The name of the field being validated, used in error reporting.

Returns

One of:

• { ok: true, value: Error }: If the value is an Error instance.
• { ok: false, field: string, message: string }: If the value is not an Error instance.

Behavior

-Accepts Error objects and all subclasses. -Rejects primitives, objects, arrays, and non-Error values. -Performs no coercion. -Never throws and never mutates input.

Examples

validateError(new Error("oops"), "err")
// { ok: true, value: Error("oops") }

validateError(new TypeError("bad type"), "err")
// { ok: true, value: TypeError("bad type") }

validateError("oops", "err")
// { ok: false, field: "err", message: "Value must be an Error" }

validateError({}, "err")
// { ok: false, field: "err", message: "Value must be an Error" }

Notes

• Suitable for validating caught errors, API inputs, or internal checks.
• Fully compatible with TypeScript strict mode.
• All error reporting uses ValidationResult.