Clear path on exception (#12335)

Should hopefully avoid it spamming in future.

Content.Server/NPC/Pathfinding/PathfindingSystem.cs

@@ -93,6 +93,8 @@ namespace Content.Server.NPC.Pathfinding
 
                 var request = _pathRequests[i];
 
+                try
+                {
                     switch (request)
                     {
                         case AStarPathRequest astar:
@@ -104,6 +106,12 @@ namespace Content.Server.NPC.Pathfinding
                         default:
                             throw new NotImplementedException();
                     }
+                }
+                catch (Exception)
+                {
+                    results[i] = PathResult.NoPath;
+                    throw;
+                }
             });
 
             var offset = 0;
@@ -123,6 +131,7 @@ namespace Content.Server.NPC.Pathfinding
                 switch (result)
                 {
                     case PathResult.Continuing:
+                        DebugTools.Assert(path.Frontier.Count > 0);
                         break;
                     case PathResult.PartialPath:
                     case PathResult.Path: