[mob][photos] Fix issue with null person data (#4713)

## Description

## Tests

mobile/lib/models/ml/face/person.dart

@@ -128,10 +128,12 @@ class PersonData {
 
   // fromJson
   factory PersonData.fromJson(Map<String, dynamic> json) {
-    final assigned = (json['assigned'] == null || json['assigned'].length == 0)
+    final assigned = (json['assigned'] == null || json['assigned'].length == 0 || json['assigned'] != Iterable)
         ? <ClusterInfo>[]
         : List<ClusterInfo>.from(
-            json['assigned'].map((x) => ClusterInfo.fromJson(x)),
+            json['assigned']
+              .where((x) => x is Map<String, dynamic>)
+              .map((x) => ClusterInfo.fromJson(x as Map<String, dynamic>)),
           );
 
     final List<String> rejectedFaceIDs =

mobile/lib/services/machine_learning/face_ml/feedback/cluster_feedback.dart

@@ -357,6 +357,7 @@ class ClusterFeedbackService {
       personID: person.remoteID,
       clusterID: clusterID,
     );
+    Bus.instance.fire(PeopleChangedEvent());
   }
 
   Future<void> ignoreCluster(String clusterID) async {

mobile/lib/ui/viewer/people/person_cluster_suggestion.dart

@@ -255,7 +255,6 @@ class _PersonClustersState extends State<PersonReviewClusterSuggestion> {
         person: widget.person,
         clusterID: clusterID,
       );
-      Bus.instance.fire(PeopleChangedEvent());
       // Increment the suggestion index
       if (mounted) {
         setState(() => currentSuggestionIndex++);

mobile/lib/ui/viewer/people/save_or_edit_person.dart

@@ -377,7 +377,6 @@ class _SaveOrEditPersonState extends State<SaveOrEditPerson> {
                               person: person.$1,
                               clusterID: widget.clusterID!,
                             );
-                            Bus.instance.fire(PeopleChangedEvent());
 
                             Navigator.pop(context, person);
                           },