bug: hasOwnProperty type guard object patch emits errors on recompile

[fahrradflucht]

This PR is just a failing test to demonstrate the bug
We want to use hasOwnProperty as a type guard so we patched Object like this:

interface Object {
  hasOwnProperty<K extends PropertyKey>(k: K): this is {[_ in K]: any }
}

This makes code like this valid:

interface TypeA {}
interface TypeB {
  bar: boolean;
}

type UnionType = TypeA | TypeB;
const foo: UnionType = {
  bar: true
}

if (!foo.hasOwnProperty('bar')) {
  throw new Error();
}

foo.bar

The problem we have is that awesome-typescript-loader (and ts-loader) emits errors as if it didn't saw the Object patch but only on recompile in watch-mode.

I wrote two tests, one that succeeds without a problem because it just compiles the code once (which demonstrates that this is a watch mode issue) and one that fails despite the fact that the only change that is made between the first compile and the incremental build is a whitespace change.