Add .empty() check in CppServiceHandler::getTags

Fixes segfault

Author: andocz

plugins/cpp/service/src/cppservice.cpp

@@ -1611,14 +1611,19 @@ CppServiceHandler::getTags(const std::vector<model::CppAstNode>& nodes_)
             tags[node.id].push_back(visibility);
         }
 
-        //--- Virtual Tag ---//
+        //--- Other Tags ---//
 
         FuncResult funcNodes = _db->query<cc::model::CppFunction>(
           FuncQuery::entityHash == defNode.entityHash);
-        const model::CppFunction& funcNode = *funcNodes.begin();
+        if(!funcNodes.empty())
+        {
+          const model::CppFunction& funcNode = *funcNodes.begin();
 
-        for (const model::Tag& tag : funcNode.tags)
-          tags[node.id].push_back(model::tagToString(tag));
+          for (const model::Tag& tag : funcNode.tags)
+            tags[node.id].push_back(model::tagToString(tag));
+        } else
+          LOG(warning) << "Database query result was not expected to be empty. "
+                       << __FILE__ << ", line #" << __LINE__;
 
         break;
       }