Check of null result value in swatch-renderer.js

There is an error when product has more than one kind of swatches:
Uncaught TypeError: Cannot read property 'oldPrice' of undefined - swatch-renderer.js:843

Steps to reproduce:
1) Set Special Price for some Simple of the Configurable product which has more than one kind of swatches, for example SKU: WJ03
2) Go to PDP (../augusta-pullover-jacket.html)
3) Select some Color and look to the console - there You will be able to see the error. This is because 'result' is null before all of the swatches are selected.

Author: aholovan

app/code/Magento/Swatches/view/frontend/web/js/swatch-renderer.js

@@ -840,13 +840,13 @@ define([
                 }
             );
 
-            if (result.oldPrice.amount !== result.finalPrice.amount) {
+            if (typeof result != 'undefined' && result.oldPrice.amount !== result.finalPrice.amount) {
                 $(this.options.slyOldPriceSelector).show();
             } else {
                 $(this.options.slyOldPriceSelector).hide();
             }
 
-            if (result.tierPrices.length) {
+            if (typeof result != 'undefined' && result.tierPrices.length) {
                 if (this.options.tierPriceTemplate) {
                     tierPriceHtml = mageTemplate(
                         this.options.tierPriceTemplate,