fix annoying warning

lib/sessions/irc.pm

@@ -262,7 +262,7 @@ sub on_speak
 
     # we remove any part processed (url and tags)
     foreach (@processed_str) {
-        $msg =~ s/\Q$_\E//;
+        $msg =~ s/\Q$_\E// if $_;
     }
 
     # and we check for command