remove extra indent from nix build

lib/widgets/avatar_or_hash.dart

@@ -62,8 +62,8 @@ class AvatarOrHash extends ConsumerWidget {
                       ),
                       fit: .cover,
                       loadingBuilder: (_, child, loadingProgress) =>
-                          loadingProgress == null ? child : box,
-                      errorBuilder: (_, _, _) => box,
+                          loadingProgress == null ? child : fallback ?? box,
+                      errorBuilder: (_, _, _) => fallback ?? box,
                     ),
             ),
           ),

lib/widgets/renderers/event.dart

@@ -67,7 +67,7 @@ class EventRenderer extends ConsumerWidget {
             MembershipContent content => switch (event.previousContent) {
               MembershipContent(:final status) =>
                 status == content.status ? null : MembershipRenderer(event),
-              _ => null,
+              _ => MembershipRenderer(event),
             },
 
             AvatarContent() => GenericEventRenderer(Icons.interests, [
@@ -80,12 +80,12 @@ class EventRenderer extends ConsumerWidget {
               Text("created the room"),
             ]),
 
-            PowerLevelsContent() => GenericEventRenderer(Icons.add, [
+            PowerLevelsContent() => GenericEventRenderer(Icons.power, [
               MessageDisplayname(event),
               Text("changed the room's power levels"),
             ]),
 
-            JoinRulesContent() => GenericEventRenderer(Icons.add, [
+            JoinRulesContent() => GenericEventRenderer(Icons.rule, [
               MessageDisplayname(event),
               Text("changed the room's join rules"),
             ]),