title: string.sub in Corona Lua crashes with ÅÄÖ
body: <p>this snippet crashes my simulator bad.</p>
  
  <pre><code>s = "stämma"
  s1 =  string.sub(s,3,3)
  print(s1)
  </code></pre>
  
  <p>It seems like it handles my character as nil, any ideas?</p>
  
  <p>Joakim</p>