Fix #1694757: calibre fails to start if the tweak tag_browser_categor…

…y_order is malformed.

src/calibre/gui2/tag_browser/model.py

@@ -994,7 +994,13 @@ def _get_category_nodes(self, sort):
  self.categories[category] = tb_categories[category]['name']
 
  # Now build the list of fields in display order
- order = tweaks['tag_browser_category_order']
+ try:
+ order = tweaks['tag_browser_category_order']
+ if not isinstance(order, dict):
+ raise TypeError()
+ except:
+ print ('Tweak tag_browser_category_order is not valid. Ignored')
+ order = {'*': 100}
  defvalue = order.get('*', 100)
  self.row_map = sorted(self.categories, key=lambda x: order.get(x, defvalue))
  return data