don't set persistid if it's empty to prevent duplicating entries

unity_package/Runtime/VelNetPersist.cs

@@ -179,7 +179,11 @@ namespace VELConnect
 
 		protected override void ReceiveState(BinaryReader binaryReader)
 		{
-			persistId = binaryReader.ReadString();
+			string newPersistId = binaryReader.ReadString();
+			if (!string.IsNullOrEmpty(newPersistId))
+			{
+				persistId = newPersistId;
+			}
 		}
 	}
 }

unity_package/package.json

@@ -1,7 +1,7 @@
 {
   "name": "edu.uga.engr.vel.vel-connect",
   "displayName": "VEL-Connect",
-  "version": "5.0.4",
+  "version": "5.0.5",
   "unity": "2019.1",
   "description": "Web-based configuration for VR applications",
   "keywords": [],