Add definitions for es6-error (#12116)

es6-error/es6-error-tests.ts

@@ -0,0 +1,15 @@
+// ES6 Error Test
+// ================================================================================
+/// <reference path="es6-error.d.ts"/>
+
+// Imports
+// --------------------------------------------------------------------------------
+import * as ExtendableError from "es6-error"
+
+class TestError extends ExtendableError {
+    constructor (message: string = "TestError") {
+        super(message)
+    }
+}
+
+throw new TestError("Test Message")

es6-error/es6-error.d.ts

@@ -0,0 +1,8 @@
+// Type definitions for es6-error v4.0.0
+// Project: https://github.com/bjyoungblood/es6-error
+// Definitions by: Karol Janyst <https://github.com/LKay>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+
+declare module "es6-error" {
+    export = Error
+}