Removed accessive id erros in tests

refs 7172db74b0 (r70370252)

- The changes referenced above changed fixtures without taking "test fixtures" in "test/utils/fixtures/fixtures.json" into account. This fix is only cosmetical to unlutter the test output with logging level set to "error". Once the referenced comment is answered a proper fix should be applied here

core/server/services/auth/setup.js

@@ -142,7 +142,10 @@ async function doFixtures(data) {
         mobiledoc = mobiledoc.replace(/{{date}}/, date);
 
         const post = await models.Post.findOne({slug: key});
+
+        if (post) {
             await models.Post.edit({mobiledoc}, {id: post.id});
+        }
     });
 
     return data;