In what cases can the Never type be used in Dart?

The Never type in Dart is used to indicate that a function or expression will never complete normally. This can happen for the following reasons:

• The function always throws an exception.
• The function contains an infinite loop.

Never is a subtype of any other type, including null. This means that a value of type Never can be assigned to a variable of any type.

Examples of usage:

1. Functions that throw an exception:

   Never throwError(String message) {
     throw Exception(message); // The function always throws an exception
   }
   

2. Functions with an infinite loop:

   Never infiniteLoop() {
     while (true) {
       // Infinite execution
     }
   }
   

Using Never helps the compiler and static analyzer better understand the flow of the program and identify potential issues. For example, if a function is marked as returning Never, the compiler can understand that code after such a function call will never be reached.