Dart is object oriented. It's sound feature helps to make codes more maintainable and readable. The sound type system means that one can never experience w state where where an expression would evaluate to a value that wouldn't match that expressions static type.
The sound system makes the code to be unambiguous. It makes the code to be easier to read as types cannot lie, also your code would be more maintainable since when a piece of code gets to be changed, you would be warned of other pieces that may have gotten broken.
