this is why you test before comitting.

systems/quote.rb

@@ -31,12 +31,12 @@ module QuoteSystem
       event.channel.send_message("##{quote[0]} <#{quote[2]}>: #{quote[3]}")
     else
       quotes = db.execute("SELECT * FROM quotes WHERE category = ?", [category])
-      if quotes == nil
+      if quotes == []
         event.channel.send_message("Uh, this is awkward. The category you're trying to get a quote from doesn't exist.")
-        return
+      else
+        quote = quotes.sample
+        event.channel.send_message("##{quote[0]}: #{quote[3]}")
       end
-      quote = quotes.sample
-      event.channel.send_message("##{quote[0]}: #{quote[3]}")
     end
     nil
   end