runner_factory library Null safety
- IsolateInitializer = FutureOr Function(Runner runner)
- Given a newly created IsolateRunner, ensures that the isolate(s) that back the Runner are initialized properly
- Produces IsolateRunner instances, including any initialization to the isolate(s) created.
P> = FutureOr Function(P param)
- Initializer that runs inside the isolate.