Thanks for the suggestions. The problem was happening in AEM 6.3. I installed AEM 6.5 and I no longer have the issue.

I can't load any page in the editor. AEM is complaining in my browser console that a component doesn't exist. That component is from a previous AEM installation. Why does my new installation still have a reference to this old component? granite.js:234 GET http://localhost:4502/content/connectapp/en/...