Improve the instance-view page in observatory.

runtime/bin/vmservice/client/lib/src/service/service.dart

Index: runtime/bin/vmservice/client/lib/src/service/service.dart
diff --git a/runtime/bin/vmservice/client/lib/src/service/service.dart b/runtime/bin/vmservice/client/lib/src/service/service.dart
index e2c9aa4e00b3e0699476c479ad709ee88b07273b..8f932e9ff002ac074cc0171a606b5038142968c0 100644
--- a/runtime/bin/vmservice/client/lib/src/service/service.dart
+++ b/runtime/bin/vmservice/client/lib/src/service/service.dart
@@ -163,6 +163,9 @@ void _upgradeObservableList(ObservableList list, VM vm, Isolate isolate) {
 /// This acts like a factory which consumes an ObservableMap and returns
 /// a fully upgraded ServiceObject.
 ServiceObject _upgradeToServiceObject(VM vm, Isolate isolate, ObservableMap m) {
+  if (!ServiceObject.isServiceMap(m)) {
+    Logger.root.severe("Malformed service object: $m");
+  }
   assert(ServiceObject.isServiceMap(m));
   var type = ServiceObject.stripRef(m['type']);
   switch (type) {
@@ -181,4 +184,4 @@ ServiceObject _upgradeToServiceObject(VM vm, Isolate isolate, ObservableMap m) {
       return isolate.classes.putIfAbsent(m);
   }
   return new ServiceMap.fromMap(isolate, m);
-}
+}