fix(lib/api/global.d.ts): update 'await-to-js' types

Adds the changes in scopsy/await-to-js#46 to our local type definitions
(which exist because I'm waiting on scopsy/await-to-js#47).

lib/api/global.d.ts

@@ -2,5 +2,5 @@ declare module 'await-to-js' {
   export default function to<T, U = Error>(
     promise: Readonly<Promise<T>>,
     errorExt?: object
-  ): Promise<[U | null, T | undefined]>;
+  ): Promise<[U, undefined] | [null, T]>;
 }