The error 'int' object is not subscriptable occurs when you attempt to use indexing or slicing on an integer, a data type which doesn’t support these operations. An integer in Python is a data type that represents a whole number. Unlike lists or dictionaries, integers do not hold a sequence of elements and therefore do not support indexing or slicing.

Two names that have been making waves with their distinct approaches to building web apps are Next.js and Vite.js. Next.js is a React framework specialized in server-side rendering (SSR), static site generation (SSG), and hybrid applications. It provides features like file-based routing, image optimization, and is particularly suited for projects where SEO and fast initial load times are priorities.

Sealed classes are a feature introduced in Java 15 which bring a new level of control and predictability to class hierarchies. A sealed class is a class that explicitly specifies which other classes are allowed to extend it. This offers a way to restrict class hierarchies, making them more predictable and less prone to unintended extensions.

The java.text.ParseException is a checked exception in Java that signals an unexpected error while parsing an input. This typically happens when the input does not match the expected format. Since ParseException is a checked exception, it must be explicitly handled in methods that can throw this exception - either by using a try-catch block or by throwing it using the throws clause.