bug: hasOwnProperty type guard object patch emits errors on recompile

src/__test__/watch-object-patch.ts

@@ -0,0 +1,94 @@
+import {
+    src, webpackConfig, tsconfig,
+    watch, expectErrors, spec
+} from './utils';
+
+spec('just patch Object interface', async function() {
+    src('index.ts', `
+        interface Object {
+            hasOwnProperty<K extends PropertyKey>(k: K): this is {[_ in K]: any }
+        }
+
+        interface TypeA {}
+        interface TypeB {
+            bar: boolean;
+        }
+
+        type UnionType = TypeA | TypeB;
+
+        const foo: UnionType = {
+            bar: true
+        }
+
+        if (!foo.hasOwnProperty('bar')) {
+            throw new Error();
+        }
+
+        foo.bar
+    `);
+
+    tsconfig();
+
+    const watcher = watch(webpackConfig());
+
+    let stats = await watcher.wait();
+    expectErrors(stats, 0);
+});
+
+spec('patch Object interface and recompile (remove empty line)', async function() {
+    const index = src('index.ts', `
+        interface Object {
+            hasOwnProperty<K extends PropertyKey>(k: K): this is {[_ in K]: any }
+        }
+
+        interface TypeA {}
+        interface TypeB {
+            bar: boolean;
+        }
+
+        type UnionType = TypeA | TypeB;
+
+        const foo: UnionType = {
+            bar: true
+        }
+
+        if (!foo.hasOwnProperty('bar')) {
+            throw new Error();
+        }
+
+        foo.bar
+    `);
+
+    tsconfig();
+
+    const watcher = watch(webpackConfig());
+
+    let stats = await watcher.wait();
+    expectErrors(stats, 0);
+
+    index.update(() => `
+        interface Object {
+            hasOwnProperty<K extends PropertyKey>(k: K): this is {[_ in K]: any }
+        }
+
+        interface TypeA {}
+        interface TypeB {
+            bar: boolean;
+        }
+
+        type UnionType = TypeA | TypeB;
+
+        const foo: UnionType = {
+            bar: true
+        }
+
+        if (!foo.hasOwnProperty('bar')) {
+            throw new Error();
+        }
+        foo.bar
+    `);
+
+    stats = await watcher.wait();
+
+    expectErrors(stats, 0);
+});