Catch NotFound and Moderated exceptions when processing scorecards in search index and its display.

app/lib/scorecard/backend.dart

@@ -73,6 +73,9 @@ class ScoreCardBackend {
   @visibleForTesting
   Future<PackageView?> getPackageView(String package) async {
     return await cache.packageView(package).get(() async {
+      if (!await packageBackend.isPackageVisible(package)) {
+        return null;
+      }
       final p = await packageBackend.lookupPackage(package);
       if (p == null) {
         _logger.warning('Package lookup failed for "$package".');
@@ -85,20 +88,24 @@ class ScoreCardBackend {
         return null;
       }
 
-      final releases = await packageBackend.latestReleases(p);
-      final pvFuture = packageBackend.lookupPackageVersion(package, version);
-      final cardFuture = scoreCardBackend.getScoreCardData(package, version);
-      await Future.wait([pvFuture, cardFuture]);
-
-      final pv = await pvFuture;
-      final card = await cardFuture;
-
-      return PackageView.fromModel(
-        package: p,
-        releases: releases,
-        version: pv,
-        scoreCard: card,
-      );
+      try {
+        final releases = await packageBackend.latestReleases(p);
+        final pvFuture = packageBackend.lookupPackageVersion(package, version);
+        final cardFuture = scoreCardBackend.getScoreCardData(package, version);
+        await Future.wait([pvFuture, cardFuture]);
+
+        final pv = await pvFuture;
+        final card = await cardFuture;
+
+        return PackageView.fromModel(
+          package: p,
+          releases: releases,
+          version: pv,
+          scoreCard: card,
+        );
+      } on NotFoundException catch (_) {
+        return null;
+      }
     });
   }
 

app/lib/search/backend.dart

@@ -171,6 +171,8 @@ class SearchBackend {
           snapshot.add(doc);
         } on RemovedPackageException catch (_) {
           snapshot.remove(package);
+        } on NotFoundException catch (_) {
+          snapshot.remove(package);
         }
       });
     }