onRestart property
Optional async callback invoked before the widget tree rebuilds.
The environment switch has already completed when this fires, so
Env.get(...) returns values from the new environment. Use this to
re-initialise services (Sentry, Dio clients, etc.) that were originally
set up in main().
The rebuild is deferred until this future completes.
Implementation
final Future<void> Function()? onRestart;