Enhance error handling and simplify group filter logic

Improved error handling in `WebContentMetaDataLoader.cs`:
- Added a `try-catch` block for JSON deserialization to handle
  `JsonSerializationException` errors.
- Logged errors using `_telemetry.LogError` and initialized
  `responseMeta` as an empty list on failure.

Simplified logic in `UserGroupsCache.cs`:
- Added early return for empty `filter.Patterns` to improve clarity.
- Removed redundant condition checks and updated comments for better
  readability and maintainability.

Author: sambetts

src/AnalyticsEngine/WebJob.Office365ActivityImporter.Engine/ActivityAPI/Loaders/WebContentMetaDataLoader.cs

@@ -85,7 +85,15 @@ public async Task<List<ActivityReportInfo>> DownloadMetadata(string changeReport
             if (!string.IsNullOrEmpty(responseFromServer))
             {
                 // Deserialise the results from the HTTP response
-                responseMeta = JsonConvert.DeserializeObject<List<ActivityReportInfo>>(responseFromServer);
+                try
+                {
+                    responseMeta = JsonConvert.DeserializeObject<List<ActivityReportInfo>>(responseFromServer);
+                }
+                catch (JsonSerializationException)
+                {
+                    _telemetry.LogError($"Could not deserialise to list of {nameof(ActivityReportInfo)} response: '{responseFromServer}'");
+                    responseMeta = new List<ActivityReportInfo>();
+                }
 
                 // Add our own batch ID variable to each response
                 foreach (var metaData in responseMeta)

src/AnalyticsEngine/WebJob.Office365ActivityImporter.Engine/Graph/User/UserGroupsCache.cs

@@ -58,11 +58,16 @@ public async Task<bool> IsInGroupsFilter(string upn, UserGroupsFilterModel filte
         {
             if (filter == null)
                 throw new ArgumentNullException(nameof(filter));
+            if (filter.Patterns.Count == 0)
+            {
+                return true; // No filter patterns - all groups match
+            }
+
             var groupsForUser = await GetGroupsForUserAsync(upn);
 
-            if (filter.Patterns.Count == 0 || groupsForUser.Count == 0)
+            if (groupsForUser.Count == 0)
             {
-                return true; // No filter patterns or user has no groups means all groups match
+                return true; // user has no groups - all groups match
             }
             return groupsForUser.Any(g => filter.Matches(g));
         }