fix: Fixes race condition with world save snapshot request (#2104)

### Summary

* Fixes a race condition where the snapshot path isn't between the request snapshot being set on a background thread, and the main loop consuming that flag.


Closes #2102

Projects/Server/World/World.cs

@@ -324,6 +324,11 @@ public static class World
         {
             _serializationStart = Core.Now;
 
+            if (string.IsNullOrEmpty(snapshotPath))
+            {
+                throw new ArgumentException("Snapshot path cannot be null or empty", nameof(snapshotPath));
+            }
+
             Persistence.SerializeAll();
             PauseSerializationThreads();
             EventSink.InvokeWorldSave();