simplify: dedupe boilerplate and remove dead code across all layers

lib/widget/async_actions/async_mixin.dart

@@ -108,10 +108,7 @@ class _InlineErrorWrapper extends StatelessWidget {
               Text(
                 err,
                 textAlign: TextAlign.center,
-                style: TextStyle(
-                  color: Theme.of(context).colorScheme.error,
-                  fontSize: 13,
-                ),
+                style: _asyncErrorTextStyle(context),
               ),
             ],
           ],