bugfixes, better background operation robustness and platform-specific error handling

lib/state/app/infrastructure/loadable_state/bloc/loadable_state_bloc.dart

@@ -27,8 +27,12 @@ class LoadableStateBloc extends Bloc<LoadableStateEvent, LoadableStateState>
       }
     });
 
-    void emitConnectivity(List<ConnectivityResult> result) =>
-        add(ConnectivityChanged(LoadableStateState(connections: result)));
+    void emitConnectivity(List<ConnectivityResult> result) {
+      // The initial checkConnectivity() future is not cancellable and may
+      // resolve after the bloc was disposed, so guard against a closed sink.
+      if (isClosed) return;
+      add(ConnectivityChanged(LoadableStateState(connections: result)));
+    }
 
     Connectivity().checkConnectivity().then(emitConnectivity);
     _updateStream = Connectivity().onConnectivityChanged.listen(
@@ -48,10 +52,10 @@ class LoadableStateBloc extends Bloc<LoadableStateEvent, LoadableStateState>
     // Re-check connectivity so the resulting [ConnectivityChanged] handler
     // clears a stale error bar and triggers [reFetch] once reachable again.
     unawaited(
-      Connectivity().checkConnectivity().then(
-        (result) =>
-            add(ConnectivityChanged(LoadableStateState(connections: result))),
-      ),
+      Connectivity().checkConnectivity().then((result) {
+        if (isClosed) return;
+        add(ConnectivityChanged(LoadableStateState(connections: result)));
+      }),
     );
   }