dwds 11.0.2 is not null safe:

This is preventing the flutter_tool from migrating to null safety.
https://github.com/flutter/flutter/blob/4a33813b3500308bb579a1dad5560971baec899f/packages/flutter_tools/lib/src/isolated/resident_web_runner.dart#L9

Note dds just published a null safe 2.0 dart-lang/sdk#45756.