Disconnected connection should be removed from active connections

Small fix that has to do with the active connections list being modified
during enumeration

Small fix

Another fix

Small simplification, should be working now

Small improvement to how OnDestroy works

Small fix

Compilation fix

:shrug-emoji:

src/SpacetimeDBClient.cs

@@ -36,7 +36,10 @@ public DbConnection Build()
             }
             conn.Connect(token, uri, nameOrAddress, compression ?? Compression.Brotli);
 #if UNITY_5_3_OR_NEWER
-            SpacetimeDBNetworkManager.ActiveConnections.Add(conn);
+            if (!SpacetimeDBNetworkManager.ActiveConnections.Contains(conn)) 
+            {
+                SpacetimeDBNetworkManager.ActiveConnections.Add(conn);
+            }
 #endif
             return conn;
         }
@@ -584,6 +587,10 @@ public void Disconnect()
             connectionClosed = true;
             webSocket.Close();
             _preProcessCancellationTokenSource.Cancel();
+
+#if UNITY_5_3_OR_NEWER
+            SpacetimeDBNetworkManager.ActiveConnections.Remove(this);
+#endif
         }
 
         /// <summary>

src/SpacetimeDBNetworkManager.cs

@@ -1,6 +1,7 @@
 #if UNITY_5_3_OR_NEWER
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using SpacetimeDB;
 using UnityEngine;
 
@@ -37,7 +38,14 @@ private void ForEachConnection(Action<IDbConnection> action)
 		}
 
 		private void Update() => ForEachConnection(conn => conn.FrameTick());
-		private void OnDestroy() => ForEachConnection(conn => conn.Disconnect());
+		private void OnDestroy()
+		{
+			// Disconnecting this connection will cause it to remove itself from ActiveConnections
+			foreach(var conn in ActiveConnections.ToList()) 
+			{
+				conn.Disconnect();
+			}
+		}
 	}
 }
 #endif