fix #15447: object is empty object type (#16290)

tests/cases/conformance/types/nonPrimitive/nonPrimitiveUnionIntersection.ts

@@ -1,5 +1,9 @@
 // @declaration: true
 var a: object & string = ""; // error
 var b: object | string = ""; // ok
+var c: object & {} = 123; // error
 a = b; // error
 b = a; // ok
+
+const foo: object & {} = {bar: 'bar'}; // ok
+const bar: object & {err: string} = {bar: 'bar'}; // error