Open With: Use a blank icon instead of erroring out on linux in case of malformed desktop files or icon themes

src/calibre/gui2/open_with.py

@@ -184,6 +184,8 @@ def choose_manually(filetype, parent):
 
     def entry_to_item(entry, parent):
         icon_path = entry.get('Icon') or I('blank.png')
+        if not isinstance(icon_path, basestring):
+            icon_path = I('blank.png')
         ans = QListWidgetItem(QIcon(icon_path), entry.get('Name') or _('Unknown'), parent)
         ans.setData(ENTRY_ROLE, entry)
         comment = (entry.get('Comment') or '')

src/calibre/utils/open_with/linux.py

@@ -191,6 +191,8 @@ def find_programs(extensions):
                     data['Icon'] = icon
                 else:
                     data.pop('Icon')
+            if not isinstance(data.get('Icon'), basestring):
+                data.pop('Icon', None)
             for k in ('Name', 'GenericName', 'Comment'):
                 val = data.get(k)
                 if val: