message: enforce non null assertion on handleSourceSelect Operator filter
diff: @@ -88,7 +88,7 @@ const RegisteredOperator: ForwardRefRenderFunction<OperatorsHandle, OperatorsPro
  setModalShow(true);
  }
  - const handleSourceSelect = async (source)=>{
  + const handleSourceSelect = async (source:string)=>{
  setProductSource(source)
  await fetchProducts(1, pageSize,
  productsQueryBase.concat([`source,string,${source},eq,true`]), selectFromAssets);
  @@ -255,7 +255,7 @@ const RegisteredOperator: ForwardRefRenderFunction<OperatorsHandle, OperatorsPro
  //alignRight
  title="Sources"
  id="dropdown-menu-align-right"
  - onSelect={async (value) => { handleSourceSelect(value)}}>
  + onSelect={async (value) => { handleSourceSelect(value!)}}>
  { productSources.map((source,index) => (
  <Dropdown.Item key={index} eventKey={source}>{source}</Dropdown.Item>
  ))}
  