When saving a node, find existing matches by looking for correct node term type

Author: jsheunis

package.json

@@ -1,6 +1,6 @@
 {
   "name": "shacl-tulip",
-  "version": "0.0.5",
+  "version": "0.0.6",
   "type": "module",
   "main": "./src/index.js",
   "module": "./src/index.js",

src/classes/FormBase.js

@@ -260,11 +260,15 @@ export class FormBase {
         if (this.content[class_uri]) {
             // If we are in edit mode, the first step is to delete existing quads from graphData
             if (editMode) {
-                RdfDS.data.graph.deleteMatches(namedNode(node_uri), null, null, null)
+                var s = this._getRecordSubjectTerm(node_uri, this.content[class_uri][node_uri])
+                if (s.termType === "NamedNode") {
+                    RdfDS.data.graph.deleteMatches(namedNode(node_uri), null, null, null)
+                } else {
+                    RdfDS.data.graph.deleteMatches(blankNode(node_uri), null, null, null)
+                }
             }
 
             // Then we generate the quads
-            
             var quads = this.formNodeToQuads(class_uri, node_uri, shapesDS)
             // and add them to the dataset
             quads.forEach(quad => {