title: Error Running IRB from Terminal on Mac - Can't find gem
body: <p>When I type irb into terminal all I get is this:</p>
  
  <pre class="lang-sh prettyprint-override"><code>Traceback (most recent call last):
      2: from /usr/local/opt/ruby/bin/irb:23:in `&lt;main&gt;'
      1: from /usr/local/lib/ruby/site_ruby/2.6.0/rubygems.rb:302:in `activate_bin_path'
  /usr/local/lib/ruby/site_ruby/2.6.0/rubygems.rb:283:in `find_spec_for_exe': can't find gem irb (&gt;= 0.a) with executable irb (Gem::GemNotFoundException)
  </code></pre>
  
  <p>I think it might be something to do with the gem library or version but can't figure it out. I am new to this and don't want to further mess things up, any help would be greatly appreciated!
  Thanks in advance!</p>