Unable to save input format settings when no vocabulary is available

Specifying a vocabulary on the input format settings pages is a requirement. When you just started using Drupal and/or the Glossary module, you might not have a vocabulary yet. Users might want to completely configure the module first instead of creating a vocabulary first. When you don't have a vocabulary yet, you do get to see the 'Select a vocabulary' text but no selection option is provided (no more then logical of course). This will confuse the users. Instead, a note that none are available would make more sense.
IMHO specifying a vocabulary doesn't really have to be a requirement. If nothing is selected, no parsing will be done.