# Buggy code
def __init__(self, *, win_id, private, parent=None):
    super().__init__(win_id, parent)
    self._win_id = win_id
    self._tab_insert_idx_left = 0
    self._tab_insert_idx_right = -1
    self.shutting_down = False
    self.tabCloseRequested.connect(self.on_tab_close_requested)
    self.new_tab_requested.connect(self.tabopen)
    self.currentChanged.connect(self.on_current_changed)
    self.cur_load_started.connect(self.on_cur_load_started)
    self.cur_fullscreen_requested.connect(self.tabBar().maybe_hide)
    self.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Expanding)
    self._undo_stack = []
    self._filter = signalfilter.SignalFilter(win_id, self)
    self._now_focused = None
    self.search_text = None
    self.search_options = {}
    self._local_marks = {}
    self._global_marks = {}
    self.default_window_icon = self.window().windowIcon()
    self.private = private
    config.instance.changed.connect(self._on_config_changed)


# 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 __init__(self, *, win_id, private, parent=None):
    super().__init__(parent)
    self.widget = tabwidget.TabWidget(win_id, parent=self)
    self._win_id = win_id
    self._tab_insert_idx_left = 0
    self._tab_insert_idx_right = -1
    self.shutting_down = False
    self.widget.tabCloseRequested.connect(self.on_tab_close_requested)
    self.widget.new_tab_requested.connect(self.tabopen)
    self.widget.currentChanged.connect(self.on_current_changed)
    self.cur_load_started.connect(self.on_cur_load_started)
    self.cur_fullscreen_requested.connect(self.widget.tabBar().maybe_hide)
    self.widget.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Expanding)
    self._undo_stack = []
    self._filter = signalfilter.SignalFilter(win_id, self)
    self._now_focused = None
    self.search_text = None
    self.search_options = {}
    self._local_marks = {}
    self._global_marks = {}
    self.default_window_icon = self.widget.window().windowIcon()
    self.private = private
    config.instance.changed.connect(self._on_config_changed)