A lot of people are worried or put off by Dart's type system, but it now also supports strong mode https://github.com/dart-lang/dev_compiler/blob/master/STRONG...
Yes, strong mode is something the Flutter team uses to help check their code.
Dart is pretty cool this way: you can scale up or down how much "typiness" you want. As your program matures, you can dial up the static type checking. Hence: strong mode.