issue #62 fixed empty node without label file can be created

Author: Rahuljagwani

src/component/modals/NodeDetails.jsx

@@ -99,7 +99,6 @@ const NodeDetails = ({
                         <input
                             className="nodeLabelFile"
                             type="text"
-                            required
                             label="Node Label file"
                             placeholder="Select file"
                             onChange={(e) => {

src/config/defaultValidators.js

@@ -1,5 +1,5 @@
 const nodeValidator = `(node, nodes, edges) => {
-    var regex = /^[A-za-z0-9]+:[A-Za-z0-9.]+$/;
+    var regex = /^[A-za-z0-9]+[:[A-Za-z0-9.]+]|[^$]$/;
     let message = { ok: true, err: null };
     if (!regex.test(node.label)) {
         message = {