[HOTFIX] fix crash when medic with healtask logs out

ReallifeGamemode.Server/Factions/Medic/Medic.cs

@@ -182,6 +182,12 @@ namespace ReallifeGamemode.Server.Factions.Medic
           {
             var medic = PlayerService.GetPlayerByNameOrId(task.MedicName);
             var victim = PlayerService.GetPlayerByNameOrId(task.Victim);
+
+            if(medic == null || victim == null)
+            {
+              continue;
+            }
+
             task.Position = victim.Position;
             medic.TriggerEvent("updateHealCheckpoint", victim.Position.X, victim.Position.Y, victim.Position.Z);
           }