Thanks for the link. I'm aware Dart currently has static typing similar to Java and C#, and has had it for some time,
My question was different though and I was asking (quoting comments further up the chain) whether "google's original plan with Dart" really was to allow for a programming language "which can be properly type-safe from the beginning".
It seems that claim about the original intent is false. I checked Wikipedia [0] which states "Dart 2.0 was released in August 2018 with language changes including a type system" and the reference they link seems to corroborate that, before 2.0, Dart didn't have a sound type system.
Thanks for prompting me to dig deeper (I probably wouldn't have done it without seeing your comment).
[0] Quote found under the history section. https://en.m.wikipedia.org/wiki/Dart_(programming_language)