[ermine] Handle exception when launching invalid component url

Change-Id: Ia57d7d14b25762179887b93d415beb34533a52e7
Reviewed-on: https://fuchsia-review.googlesource.com/c/experiences/+/430757
Reviewed-by: Chase Latta <chaselatta@google.com>
Testability-Review: Chase Latta <chaselatta@google.com>
Commit-Queue: Sanjay Chouksey <sanjayc@google.com>
diff --git a/session_shells/ermine/shell/lib/src/models/ermine_story.dart b/session_shells/ermine/shell/lib/src/models/ermine_story.dart
index 87de475..d507f75 100644
--- a/session_shells/ermine/shell/lib/src/models/ermine_story.dart
+++ b/session_shells/ermine/shell/lib/src/models/ermine_story.dart
@@ -181,6 +181,6 @@
 
       await viewRefService.watch(ViewRef(reference: eventPair));
       childViewConnection.requestFocus();
-    } on Error catch (_) {}
+    } on Exception catch (_) {}
   }
 }