title: How do I scale the stack when debugging with byebug?
body: <p>I'm currently getting an error that looks like this:</p>
  
  <pre class="lang-none prettyprint-override"><code>NoMethodError: undefined method `debug' for nil:NilClass
      /mnt/hgfs/Dropbox/Company/Project/lib/project/misc.rb:23:in `debug'
      /mnt/hgfs/Dropbox/Company/Project/lib/project/validation/google_geocoding_validation_engine.rb:49:in `block in compare_addresses'
      /mnt/hgfs/Dropbox/Company/Project/lib/project/validation/google_geocoding_validation_engine.rb:43:in `each'
      /mnt/hgfs/Dropbox/Company/Project/lib/project/validation/google_geocoding_validation_engine.rb:43:in `compare_addresses'
      /mnt/hgfs/Dropbox/Company/Project/lib/project/validation/google_geocoding_validation_engine.rb:32:in `valid?'
      /mnt/hgfs/Dropbox/Company/Project/specs/project/validation/google_geocoding_validation_engine_spec.rb:56:in `block (2 levels) in &lt;module:Validation&gt;'
      /home/tomas/ruby2/lib/ruby/2.0.0/minitest/unit.rb:1301:in `run'
  </code></pre>
  
  <p>I figured I'd try using <a href="https://github.com/deivid-rodriguez/byebug" rel="nofollow">byebug</a> to figure out why the object is <code>nil</code> since it's never supposed to be <code>nil</code>. I placed <code>byebug</code> just above the erroneous line:</p>
  
  <pre><code>def debug(&amp;block)
    if @logger.nil?
      byebug
    end
  
    @logger.debug(@logger_name, &amp;block)
  end
  </code></pre>
  
  <p>And ran the tests. I was dropped to the byebug debugging interface and could confirm that the object was indeed <code>nil</code>. The problem is that I can't climb up the stack:</p>
  
  <pre class="lang-none prettyprint-override"><code>(byebug) up
  *** Adjusting would put us beyond the oldest (initial) frame.
  (byebug) down
  *** Adjusting would put us beyond the newest (innermost) frame.
  (byebug) backtrace
  --&gt; #0  AddressKit::Misc::Logging.debug(block#Proc) at /mnt/hgfs/Dropbox/Kvantel/Address Kit/lib/addresskit/misc.rb:25
  Warning: saved frames may be incomplete; compare with caller(0)
  </code></pre>
  
  <p>Why can't I go up the stack? Is this an issue with byebug or perhaps an incompatibility with MiniTest?</p>