title: Error concatenating strings
body: <p>I am trying to create a deck of cards. Early in my code I have the following.</p>
  
  <pre><code>suits = {"c","d","h","s"}
  </code></pre>
  
  <p>And I try to create the cards as follows</p>
  
  <pre><code>cardDeck = {};
  for i=0, 3 do
     for j=1, 13 do
        local newCard = suits[i]..j;
     end
  end
  </code></pre>
  
  <p>I get the following error: <code>Attempt to concatenate field '?' (a nil value)</code></p>