Incorrect Definition for Window.onError

[danjohnso]

Search Terms:
window.onerror

The interface is incorrect for window.onerror. If there is a thrown error like:
throw "This is an error";

Then the type of error is string. The spec for this interface is that error can be any, not just a nullable error. I think the interface should be changed to match spec, or at least allow a string type error:

interface ErrorEventHandler {
    (event: Event | string, source?: string, fileno?: number, columnNumber?: number, error?: Error | string): void;
}

Expected behavior:
https://html.spec.whatwg.org/multipage/webappapis.html#errorevent
interface ErrorEvent : Event {
readonly attribute DOMString message;
readonly attribute USVString filename;
readonly attribute unsigned long lineno;
readonly attribute unsigned long colno;
readonly attribute any error;
};

Actual behavior:
interface ErrorEventHandler {
(event: Event | string, source?: string, fileno?: number, columnNumber?: number, error?: Error): void;
}

Related Issues:
#2838

[weswigham]

PRs welcomed. You can find more information about contributing lib.d.ts fixes at https://github.com/Microsoft/TypeScript/blob/master/CONTRIBUTING.md#contributing-libdts-fixes.