title: An error appears under my project name but no error exists?
body: <p>What basically happens is an error (little red cross) appears under my project name as if there was an error somewhere. When I look into my project, no errors, and when I run my code, no errors, it works perfectly fine.
  Can someone explain to me how I can fix it? And what it means?</p>
  
  <p>I'm using Eclipse Luna.</p>
  
  <p><img src="https://i.stack.imgur.com/RxHMr.png" alt="enter image description here"></p>