title: Constantize raises Uninitialized Constant Error
body: <p>I'm working on <a href="https://stackoverflow.com/questions/20674714/creating-a-module-for-raising-class-specific-errors">this pretty thorny problem</a> and decided I might be able to dynamically create a class that inherits from StandardError by doing this:</p>
  
  <pre><code>something = "JustForBelow"
  error_class = "#{something}Error".constantize
  error_class = StandardError.new
  </code></pre>
  
  <p>But I'm getting a really weird error (in my opinion), which is:</p>
  
  <pre><code>Uninitialized constant JustForBelowError
  </code></pre>
  
  <p>Aren't I initializing it right there?</p>
  
  <p>(Essentially) same error comes up when I try this:</p>
  
  <pre><code>StandardError.const_get "#{something}Error"
  # =&gt; NameError: uninitialized constant StandardError::JustForBelowClass
  </code></pre>
  
  <p>This feels really weird, because a) these are super random names; there aren't any conflicts, and b) I'm pretty sure I've used constantize like in the first example before. Any ideas what's going wrong?</p>