DeadPlayersAPI [Unmaintained]

Just a tip: All of the using statements excluding Oxide.Core.Plugins in your example can be removed, as can the first null check, as you're already checking for null in the line right after it via null propagation.

Code:

using Oxide.Core.Plugins;namespace Oxide.Plugins
{
    [Info("DeadPlayerPreventTP", "Prefix", "0.1.0")]
    class DeadPlayerPreventTP : RustLegacyPlugin
    {
        [PluginReference] Plugin DeadPlayersAPI;        object CanTeleport(NetUser netuser)
        {
            var isdead = DeadPlayersAPI?.Call("IsDead", netuser);
            if (isdead != null && (bool)isdead) return false;
            return null;
        }
    }
}