# Buggy code
def _tab_close(self, tab, prev=False, next_=False, opposite=False):
    """Helper function for tab_close be able to handle message.async.

    Args:
        tab: Tab object to select be closed.
        prev: Force selecting the tab before the current tab.
        next_: Force selecting the tab after the current tab.
        opposite: Force selecting the tab in the opposite direction of
                  what's configured in 'tabs.select_on_remove'.
        count: The tab index to close, or None
    """
    tabbar = self._tabbed_browser.tabBar()
    selection_override = self._get_selection_override(prev, next_, opposite)

    if selection_override is None:
        self._tabbed_browser.close_tab(tab)
    else:
        old_selection_behavior = tabbar.selectionBehaviorOnRemove()
        tabbar.setSelectionBehaviorOnRemove(selection_override)
        self._tabbed_browser.close_tab(tab)
        tabbar.setSelectionBehaviorOnRemove(old_selection_behavior)


# Traceback (ValueError)
16:39:44 DEBUG    init       app:_init_modules:468 Initializing websettings...
16:39:45 ERROR    misc       crashsignal:exception_hook:216 Uncaught exception
Traceback (most recent call last):
File "/bin/qutebrowser", line 11, in <module>
load_entry_point('qutebrowser==1.1.1', 'gui_scripts', 'qutebrowser')()
File "/usr/lib/python3.6/site-packages/qutebrowser/qutebrowser.py", line 188, in main
return app.run(args)
File "/usr/lib/python3.6/site-packages/qutebrowser/app.py", line 137, in run
init(args, crash_handler)
File "/usr/lib/python3.6/site-packages/qutebrowser/app.py", line 163, in init
_init_modules(args, crash_handler)
File "/usr/lib/python3.6/site-packages/qutebrowser/app.py", line 469, in _init_modules
websettings.init(args)
File "/usr/lib/python3.6/site-packages/qutebrowser/config/websettings.py", line 215, in init
webenginesettings.init(args)
File "/usr/lib/python3.6/site-packages/qutebrowser/browser/webengine/webenginesettings.py", line 297, in init
websettings.init_mappings(MAPPINGS)
File "/usr/lib/python3.6/site-packages/qutebrowser/config/websettings.py", line 198, in init_mappings
mapping.set(value)
File "/usr/lib/python3.6/site-packages/qutebrowser/config/websettings.py", line 72, in set
self._set(value, settings=settings)
File "/usr/lib/python3.6/site-packages/qutebrowser/browser/webengine/webenginesettings.py", line 154, in _set
filenames = [self._find_installed(code) for code in value]
File "/usr/lib/python3.6/site-packages/qutebrowser/browser/webengine/webenginesettings.py", line 154, in <listcomp>
filenames = [self._find_installed(code) for code in value]
File "/usr/lib/python3.6/site-packages/qutebrowser/browser/webengine/webenginesettings.py", line 143, in _find_installed
local_filename = spell.local_filename(code)
File "/usr/lib/python3.6/site-packages/qutebrowser/browser/webengine/spell.py", line 64, in local_filename
all_installed = local_files(code)
File "/usr/lib/python3.6/site-packages/qutebrowser/browser/webengine/spell.py", line 51, in local_files
for matching_dict in sorted(matching_dicts, key=version, reverse=True):
File "/usr/lib/python3.6/site-packages/qutebrowser/browser/webengine/spell.py", line 36, in version
.format(filename))
ValueError: the given dictionary file name is malformed: /usr/share/qt/qtwebengine_dictionaries/en-US.bdic

# Fixed code
def _tab_close(self, tab, prev=False, next_=False, opposite=False):
    """Helper function for tab_close be able to handle message.async.

    Args:
        tab: Tab object to select be closed.
        prev: Force selecting the tab before the current tab.
        next_: Force selecting the tab after the current tab.
        opposite: Force selecting the tab in the opposite direction of
                  what's configured in 'tabs.select_on_remove'.
        count: The tab index to close, or None
    """
    tabbar = self._tabbed_browser.widget.tabBar()
    selection_override = self._get_selection_override(prev, next_, opposite)

    if selection_override is None:
        self._tabbed_browser.close_tab(tab)
    else:
        old_selection_behavior = tabbar.selectionBehaviorOnRemove()
        tabbar.setSelectionBehaviorOnRemove(selection_override)
        self._tabbed_browser.close_tab(tab)
        tabbar.setSelectionBehaviorOnRemove(old_selection_behavior)