Merge pull request #574 from lunarraid/bugfix/563-add-writable-to-read-only-check

Add 'writable' descriptor check to isReadOnlyProperty

Author: trezy

src/helpers/isReadOnlyProperty.ts

@@ -6,5 +6,5 @@ export function isReadOnlyProperty(
     const prototype = Object.getPrototypeOf(objectInstance);
     const propertyDescriptor = Object.getOwnPropertyDescriptor(prototype, propertyKey);
 
-    return !(typeof propertyDescriptor === 'undefined' || propertyDescriptor.set);
+    return !(typeof propertyDescriptor === 'undefined' || propertyDescriptor.writable || propertyDescriptor.set);
 }