# Buggy code
def _filter_signals(self, signal, tab, *args):
    """Filter signals and trigger TabbedBrowser signals if needed.

    Triggers signal if the original signal was sent from the _current_ tab
    and not from any other one.

    The original signal does not matter, since we get the new signal and
    all args.

    Args:
        signal: The signal to emit if the sender was the current widget.
        tab: The WebView which the filter belongs to.
        *args: The args to pass to the signal.
    """
    log_signal = debug.signal_name(signal) not in self.BLACKLIST
    tabbed_browser = objreg.get("tabbed-browser", scope="window", window=self._win_id)
    try:
        tabidx = tabbed_browser.indexOf(tab)
    except RuntimeError:
        # The tab has been deleted already
        return
    if tabidx == tabbed_browser.currentIndex():
        if log_signal:
            log.signals.debug(
                "emitting: {} (tab {})".format(debug.dbg_signal(signal, args), tabidx)
            )
        signal.emit(*args)
    else:
        if log_signal:
            log.signals.debug(
                "ignoring: {} (tab {})".format(debug.dbg_signal(signal, args), tabidx)
            )


# 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 _filter_signals(self, signal, tab, *args):
    """Filter signals and trigger TabbedBrowser signals if needed.

    Triggers signal if the original signal was sent from the _current_ tab
    and not from any other one.

    The original signal does not matter, since we get the new signal and
    all args.

    Args:
        signal: The signal to emit if the sender was the current widget.
        tab: The WebView which the filter belongs to.
        *args: The args to pass to the signal.
    """
    log_signal = debug.signal_name(signal) not in self.BLACKLIST
    tabbed_browser = objreg.get("tabbed-browser", scope="window", window=self._win_id)
    try:
        tabidx = tabbed_browser.widget.indexOf(tab)
    except RuntimeError:
        # The tab has been deleted already
        return
    if tabidx == tabbed_browser.widget.currentIndex():
        if log_signal:
            log.signals.debug(
                "emitting: {} (tab {})".format(debug.dbg_signal(signal, args), tabidx)
            )
        signal.emit(*args)
    else:
        if log_signal:
            log.signals.debug(
                "ignoring: {} (tab {})".format(debug.dbg_signal(signal, args), tabidx)
            )