# Buggy code
def log_signals(obj):
    """Log all signals of an object or class.

    Can be used as class decorator.
    """

    def log_slot(obj, signal, *args):
        """Slot connected to a signal to log it."""
        dbg = dbg_signal(signal, args)
        try:
            r = repr(obj)
        except RuntimeError:  # pragma: no cover
            r = "<deleted>"
        log.signals.debug("Signal in {}: {}".format(r, dbg))

    def connect_log_slot(obj):
        """Helper function to connect all signals to a logging slot."""
        metaobj = obj.metaObject()
        for i in range(metaobj.methodCount()):
            meta_method = metaobj.method(i)
            qtutils.ensure_valid(meta_method)
            if meta_method.methodType() == QMetaMethod.Signal:
                name = bytes(meta_method.name()).decode("ascii")
                if name != "destroyed":
                    signal = getattr(obj, name)
                    try:
                        signal.connect(functools.partial(log_slot, obj, signal))
                    except TypeError:  # pragma: no cover
                        pass

    if inspect.isclass(obj):
        old_init = obj.__init__

        @functools.wraps(old_init)
        def new_init(self, *args, **kwargs):
            """Wrapper for __init__() which logs signals."""
            ret = old_init(self, *args, **kwargs)
            connect_log_slot(self)
            return ret

        obj.__init__ = new_init
        return obj
    else:
        connect_log_slot(obj)


# 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 log_signals(obj):
    """Log all signals of an object or class.

    Can be used as class decorator.
    """

    def log_slot(obj, signal, *args):
        """Slot connected to a signal to log it."""
        dbg = dbg_signal(signal, args)
        try:
            r = repr(obj)
        except RuntimeError:  # pragma: no cover
            r = "<deleted>"
        log.signals.debug("Signal in {}: {}".format(r, dbg))

    def connect_log_slot(obj):
        """Helper function to connect all signals to a logging slot."""
        metaobj = obj.metaObject()
        for i in range(metaobj.methodCount()):
            meta_method = metaobj.method(i)
            qtutils.ensure_valid(meta_method)
            if meta_method.methodType() == QMetaMethod.Signal:
                name = bytes(meta_method.name()).decode("ascii")
                if name != "destroyed":
                    signal = getattr(obj, name)
                    try:
                        signal.connect(functools.partial(log_slot, obj, signal))
                    except TypeError:  # pragma: no cover
                        pass

    if inspect.isclass(obj):
        old_init = obj.__init__

        @functools.wraps(old_init)
        def new_init(self, *args, **kwargs):
            """Wrapper for __init__() which logs signals."""
            ret = old_init(self, *args, **kwargs)
            connect_log_slot(self)
            return ret

        obj.__init__ = new_init
    else:
        connect_log_slot(obj)

    return obj