Fix list select (with choicesjs) losing values in subform (joomla#42332)

Author: Fedik

build/media_source/system/js/fields/joomla-field-fancy-select.w-c.es6.js

@@ -103,6 +103,7 @@ window.customElements.define('joomla-field-fancy-select', class extends HTMLElem
       if (this.isDisconnected) {
         // Re init previous instance
         this.choicesInstance.init();
+        this.choicesInstance.setChoiceByValue(this.disconnectValues);
         this.isDisconnected = false;
       }
       return;
@@ -275,6 +276,8 @@ window.customElements.define('joomla-field-fancy-select', class extends HTMLElem
   disconnectedCallback() {
     // Destroy Choices instance, to unbind event listeners
     if (this.choicesInstance) {
+      // Keep selected values, because choices will reset them on re-init
+      this.disconnectValues = this.choicesInstance.getValue(true);
       this.choicesInstance.destroy();
       this.isDisconnected = true;
     }