Fix Timestamps Query in EntityQueryProcessor

source/RobotAPI/libraries/armem/query/EntityQueryProcessor.cpp

@@ -25,6 +25,10 @@ namespace armarx::armem
         {
             process(result, *q, entity);
         }
+        else if (auto q = dynamic_cast<const query::entity::Timestamps*>(&query))
+        {
+            process(result, *q, entity);
+        }
         else
         {
             throw armem::error::UnknownQueryType("entity snapshot", query);
@@ -86,7 +90,7 @@ namespace armarx::armem
         {
             if (timestampsOnly)
             {
-                result.history.emplace(it->second->time, nullptr);
+                result.addSnapshot(std::make_unique<EntitySnapshot>(it->second->time));
             }
             else
             {