misc: eliminate the warning of invalid map<K, T> key (map::at)

GitLab: #160

Change-Id: Ib2de72037d2e0b5fc7c29e5686f9336bbc7ed035

src/smartlistmodel.cpp

@@ -343,7 +343,7 @@ SmartListModel::getConversationItemData(const conversation::Info& item,
     }
     case Role::CallStackViewShouldShow: {
         const auto& convInfo = lrcInstance_->getConversationFromConvUid(item.uid);
-        if (!convInfo.uid.isEmpty()) {
+        if (!convInfo.uid.isEmpty() && !convInfo.callId.isEmpty()) {
             auto* callModel = lrcInstance_->getCurrentCallModel();
             const auto& call = callModel->getCall(convInfo.callId);
             return QVariant(