TKey can not be null.

Pathfinding/RPriorityQueue.cs

@@ -3,7 +3,7 @@ namespace Pathfinding;
 public class RPriorityQueue<TKey, TPriority> where TKey : notnull
 {
     public Dictionary<TKey, TPriority> queue;
-    public int Count { get; private set; }
+    public int Count => queue.Count;
 
     public RPriorityQueue()
     {
@@ -14,14 +14,12 @@ public class RPriorityQueue<TKey, TPriority> where TKey : notnull
     {
         if (!queue.TryAdd(key, priority))
             queue[key] = priority;
-        Count = queue.Count;
     }
 
-    public TKey? Dequeue()
+    public TKey Dequeue()
     {
-        TKey? retKey = queue.MinBy(item => item.Value).Key;
+        TKey retKey = queue.MinBy(item => item.Value).Key;
         queue.Remove(retKey);
-        Count = queue.Count;
         return retKey;
     }
 
@@ -30,7 +28,6 @@ public class RPriorityQueue<TKey, TPriority> where TKey : notnull
         int before = Count;
         queue = queue.Where(queueitem => !elements.Contains(queueitem.Key))
             .ToDictionary(item => item.Key, item => item.Value);
-        Count = queue.Count;
         return before - Count;
     }
 
@@ -38,7 +35,6 @@ public class RPriorityQueue<TKey, TPriority> where TKey : notnull
     {
         int before = Count;
         queue = queue.IntersectBy(exceptKeys, item => item.Key).ToDictionary(item => item.Key, item => item.Value);
-        Count = queue.Count;
         return before - Count;
     }