Resolve "optimiser la sauvegarde/restauration des paramètres"

Closes #510 (closed)

src/app/components/fieldset-container/fieldset-container.component.ts

@@ -83,9 +83,9 @@ export class FieldsetContainerComponent implements DoCheck, AfterViewInit {
      * dans un nouveau fieldset
      */
     private addSubNub(after: FieldSet, clone: boolean = false) {
-        const prms = clone ? after.backupParameters() : undefined;
         const newFs = this._container.addFromTemplate(0, after.indexAsKid());
         if (clone) {
+            const prms = after.backupParameters();
             // replace in-place to change properties (overkill)
             // @WTF why only those two ?
             newFs.setPropValue("structureType", after.properties.getPropValue("structureType"));