graph algo: fix Dijkstra's algo

alib2graph_algo/src/shortest_path/Dijkstra.hpp

@@ -292,10 +292,12 @@ bool Dijkstra::relaxation(FEdges successor_edges,
     // If not or the distance can be improve do relaxation
     if (search_d == data.g.end() || search_d->second > gscore) {
       // Search if the node s is in OPEN
-      auto search_q = data.queue.find(ext::make_pair(search_d->second, s));
-      if (search_q != data.queue.end()) {
-        // Erase node from priority queue
-        data.queue.erase(search_q);
+      if (search_d != data.g.end()) {
+        auto search_q = data.queue.find(ext::make_pair(search_d->second, s));
+        if (search_q != data.queue.end()) {
+          // Erase node from priority queue
+          data.queue.erase(search_q);
+        }
       }
       data.g[s] = gscore;