Address code review feedback

app/assets/javascripts/static_site_editor/graphql/resolvers/submit_content_changes.js

@@ -17,8 +17,6 @@ const submitContentChangesResolver = (
           },
         },
       });
-
-      return null;
     },
   );
 };

spec/frontend/static_site_editor/pages/home_spec.js

@@ -137,7 +137,7 @@ describe('static_site_editor/pages/home', () => {
     expect(findInvalidContentMessage().exists()).toBe(true);
   });
 
-  it('does not display invalid content message when content is not supported', () => {
+  it('does not display invalid content message when content is supported', () => {
     buildWrapper({ appData: { isSupportedContent: true } });
 
     expect(findInvalidContentMessage().exists()).toBe(false);