magento/magento2#8114: "Save Block"-button on Add New Block silently ignores...

magento/magento2#8114: "Save Block"-button on Add New Block silently ignores clicks if the content is empty.

app/code/Magento/Ui/view/base/web/js/form/components/html.js

@@ -19,6 +19,7 @@ define([
             showSpinner:    false,
             loading:        false,
             visible:        true,
+            error:          false,
             template:       'ui/content/content',
             additionalClasses: {}
         },