Added checks for empty tweet messages.

src/org/april/hebdobot/model/Hebdobot.java

@@ -202,7 +202,7 @@ public class Hebdobot extends PircBot
      */
     public void notifyTwitter(final String message)
     {
-        if (this.twitterSettings.isValid())
+        if ((this.twitterSettings.isValid()) && (StringUtils.isNotBlank(message)))
         {
             try
             {

src/org/april/hebdobot/twitter/TwitterClient.java

@@ -88,6 +88,12 @@ public class TwitterClient
      *             the twitter exception
      */
     public void tweet(final String message) throws TwitterException
+    {
+        if (StringUtils.isBlank(message))
+        {
+            logger.info("Empty message => tweet aborted.");
+        }
+        else
         {
             ConfigurationBuilder config = new ConfigurationBuilder();
             config.setDebugEnabled(true);
@@ -102,3 +108,4 @@ public class TwitterClient
             logger.info("Tweet result [" + status.getText() + "].");
         }
     }
+}