# Buggy code
def _update_settings(option):
    """Update global settings when qwebsettings changed."""
    global_settings.update_setting(option)

    if option in ["scrolling.bar", "content.user_stylesheets"]:
        _init_stylesheet(default_profile)
        _init_stylesheet(private_profile)
        _update_stylesheet()
    elif option in ["content.headers.user_agent", "content.headers.accept_language"]:
        _set_http_headers(default_profile)
        _set_http_headers(private_profile)
    elif option == "content.cache.size":
        _set_http_cache_size(default_profile)
        _set_http_cache_size(private_profile)
    elif (
        option == "content.cookies.store"
        and
        # https://bugreports.qt.io/browse/QTBUG-58650
        qtutils.version_check("5.9", compiled=False)
    ):
        _set_persistent_cookie_policy(default_profile)
        # We're not touching the private profile's cookie policy.
    elif option == "spellcheck.languages":
        _set_dictionary_language(default_profile)
        _set_dictionary_language(private_profile, warn=False)


# 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 _update_settings(option):
    """Update global settings when qwebsettings changed."""
    global_settings.update_setting(option)

    if option in ["content.headers.user_agent", "content.headers.accept_language"]:
        default_profile.setter.set_http_headers()
        private_profile.setter.set_http_headers()
    elif option == "content.cache.size":
        default_profile.setter.set_http_cache_size()
        private_profile.setter.set_http_cache_size()
    elif (
        option == "content.cookies.store"
        and
        # https://bugreports.qt.io/browse/QTBUG-58650
        qtutils.version_check("5.9", compiled=False)
    ):
        default_profile.setter.set_persistent_cookie_policy()
        # We're not touching the private profile's cookie policy.
    elif option == "spellcheck.languages":
        default_profile.setter.set_dictionary_language()
        private_profile.setter.set_dictionary_language(warn=False)