Problem using `var` in Dart

var_problem.dart

void main() {
  final list = <int>[1, 2, 3, 4, 2, -1, 5];
  final maxValue = 12;
  
  var sum = 0;
  for(final val in list) {
    sum += val;
  }
  if(sum > maxValue) {
    sum = maxValue;
  }
  
  // The code can use `sum` but allowing the mutation.
  // It can drive developers to unintentional errors.
  
  /// ... more code that uses `sum` ...
}