title: What is causing the compile error: Illegal NSTableView data source?
body: <p>After some 'cleaning' of a working app, the main window appears as designed in the <code>MainWindow.xib</code>. </p>
  
  <ul>
  <li>I deleted a MainWindowViewController object in IB. (was beneath Font Manager)</li>
  <li>MainWindow.xib has it's Custom class set to <code>MainWindowViewController</code></li>
  <li>The table uses Content Mode - View Based </li>
  <li>The two required  methods ARE included in that implementation file</li>
  <li> included in header file</li>
  <li>Table view connection has been made to <code>File's Owner</code></li>
  </ul>
  
  <p>EDIT: Does the full error message give a clue? Why the NSApplication?</p>
  
  <pre><code>*** Illegal NSTableView data source (&lt;NSApplication: 0x100607ad0&gt;).
  </code></pre>
  
  <p>What am I missing? What should I check to resolve?</p>
  
  <p>Image included to help visualize.</p>
  
  <p><img src="https://i.stack.imgur.com/9djSM.png" alt="Screenshot of MainWindow.xib"></p>
  
  <p>EDIT 2: (New info)</p>
  
  <p>I deleted the <code>data source</code> &amp; <code>delegate</code> connection from the table view and the error disappeared. The same IB designed window opens with an empty table view. </p>