Finalizing Server webUI

Still needed:
- Way to update clients' versions
- Way to delete nodes
- working dashboard
- working search function

Server/controllers/adminController.js

@@ -86,6 +86,8 @@ exports.leaveServer = async (req, res) => {
     const currentConnection = await getConnectionByNodeId(nodeId);
     log.DEBUG("Current Connection for node: ", currentConnection);
 
+	if (!currentConnection) return res.status(400).json("Node is not connected")
+
     await leaveServerWrapper(currentConnection.clientObject)
 
     return res.status(200).json(currentConnection.clientObject.name);