Issues in generating a ComboBox within WAB Widget

BenHahn

Hi everyone,

I am pretty new to WAB and Javacript development with Dojo. My plan is to generate a dynamic Combobox out of feature-layer attributes. On click the widget should add that specific feature-layer with the chosen layerexpression. e.g. Country selection ComboBox: "USA" -> Zoom on USA.

I got this to work in a standalone Javascript api, but now i'd like to include this into my WAB1.2 functionality set as a widget and I ran into several Dojo issues which I am not familiar with.

Basically I started a new widget from scratch:

Widget.js

define([
    'dojo/_base/declare', 
    'jimu/BaseWidget', 
    'jimu/ConfigManager', 
    "jimu/WidgetManager",    
    'esri/layers/FeatureLayer',  
    "dijit/form/Select",
    "dojo/query", 
    "dojo/ready", 
    "dijit/form/ComboBox", 
    "dojo/data/ItemFileReadStore", 
    "dojo/_base/array", 
    "dojo/on"
    ],
    
function(
    declare, 
    BaseWidget,
    ConfigManager,  
    WidgetManager,
    FeatureLayer, 
    Select,
    query, 
    ready,
    ComboBox, 
    ItemFileReadStore, 
    array, 
    on
    
) {
  return declare([BaseWidget], {
        baseClass: 'definition_query',  
        onOpen: function () {  

            function init() {
               queryTask = new esri.tasks.QueryTask