title: Variable return as nil
body: <p>I'm confused by this error.  I'm writing a lua script for mocp to display info in conky.  When I play music files in "/media/Stuff/old-music" everything works fine but I get an error when I play music files in "/home/tony/Music".  None of the directories are hard coded in my script.  The error says a variable is returned as nil.  I check and the music file has the required info.  Why am I getting this error?</p>
  
  <p>error..</p>
  
  <p>Conky: llua_do_call: function conky_main execution failed: /home/tony/.conky/lua-test/albumart.lua:68: attempt to concatenate global 'album' (a nil value)</p>
  
  <p>code...</p>
  
  <pre><code>....
  totaltime,totaltimesecs,song,artist,album,albumart=newsong(update_num)
  ....
  function newsong()
      local f = io.popen("mocp -Q %album")
      album= f:read("*a")
      f:close()
      album=string.gsub(album,"[\n]","")
      local f = io.popen("mocp -Q %artist")
      artist= f:read("*a")
      f:close()
      artist=string.gsub(artist,"[\n]","")
      local f = io.popen("mocp -Q %song")
      song= f:read("*a")
      f:close()
      song=string.gsub(song,"[\n]","")
      local f = io.popen("mocp -Q %tt")
      totaltime= f:read("*a")
      f:close()
      totaltime=string.gsub(totaltime,"[\n]","")
      local f = io.popen("mocp -Q %ts")
      totaltimesecs= f:read("*a")
      f:close()
      totaltime=string.gsub(totaltime,"[\n]","")
  return totaltime,totaltimesecs,song,artist,album,albumart
  </code></pre>