Fix crash when ending cluster is not found - has no route to it

CriticalPathAnalyzer/CriticalPathAnalyzer/src/server/tool/ServerPathTracer.cs

@@ -57,6 +57,7 @@ namespace CriticalPathAnalyzer.Server.Tool {
             var clusterNodes = new List<ClusterNode>();
             var clusterToNodeMapping = new Dictionary<Cluster, int>(); // Cluster / index of node
             var queue = new Queue<ClusterNode>();
+            var loopingNodes = new HashSet<int>();
 
             // An input peg, only has a single cluster.
             // An output peg however can be connected to multiple clusters.
@@ -125,6 +126,8 @@ namespace CriticalPathAnalyzer.Server.Tool {
                         // only add the link, don't propagate
                         if (!nextNode.PrevNodeIndexes.Add(node.Index)) {
                             logger.Warn("Loop detected");
+                            loopingNodes.Add(node.Index);
+                            loopingNodes.Add(nextNode.Index);
                             // already been here - there is a cycle
                             continue;
                         }
@@ -161,13 +164,22 @@ namespace CriticalPathAnalyzer.Server.Tool {
                 }
             }
 
+            // Attempt to get the critical path length
+            // If the ending cluster has not been found, return -1
+            Cluster endingCluster = endingClusters.First();
+            int criticalPathLength = -1;
+            if (clusterToNodeMapping.TryGetValue(endingCluster, out int nodeIndex)) {
+                criticalPathLength = clusterNodes[nodeIndex].Time;
+            }
+
             // Collect information about each cluster:
             response = new AnalyzePathResponse() {
                 RequestGuid = requestGuid,
                 Clusters = clusterNodes.SelectMany(node =>
                     node.Clusters.Select(cluster => CollectClusterInformation(cluster, node.Time))).ToList(),
-                CriticalPathLength = clusterNodes[clusterToNodeMapping[endingClusters.First()]].Time,
-
+                CriticalPathLength = criticalPathLength,
+                LoopingClusters = loopingNodes.SelectMany(loopingNodeIndex => clusterNodes[loopingNodeIndex].Clusters
+                    .Select(cluster => CollectClusterInformation(cluster, 0))).ToList(),
                 // PerimeterComponents = perimeterComponents.ToList(),
                 // NextClusters = collectedNextClusters.Select(CollectClusterInformation).ToList(),
             };