# Buggy code
def _on_mode_entered(self, mode):
    if mode != usertypes.KeyMode.caret:
        return

    settings = self._widget.settings()
    settings.setAttribute(QWebSettings.CaretBrowsingEnabled, True)
    self.selection_enabled = self._widget.hasSelection()

    if self._widget.isVisible():
        # Sometimes the caret isn't immediately visible, but unfocusing
        # and refocusing it fixes that.
        self._widget.clearFocus()
        self._widget.setFocus(Qt.OtherFocusReason)

        # Move the caret to the first element in the viewport if there
        # isn't any text which is already selected.
        #
        # Note: We can't use hasSelection() here, as that's always
        # true in caret mode.
        if not self.selection_enabled:
            self._widget.page().currentFrame().evaluateJavaScript(
                utils.read_file("javascript/position_caret.js")
            )


# 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 _on_mode_entered(self, mode):
    if mode != usertypes.KeyMode.caret:
        return

    self.selection_enabled = self._widget.hasSelection()
    self.selection_toggled.emit(self.selection_enabled)
    settings = self._widget.settings()
    settings.setAttribute(QWebSettings.CaretBrowsingEnabled, True)

    if self._widget.isVisible():
        # Sometimes the caret isn't immediately visible, but unfocusing
        # and refocusing it fixes that.
        self._widget.clearFocus()
        self._widget.setFocus(Qt.OtherFocusReason)

        # Move the caret to the first element in the viewport if there
        # isn't any text which is already selected.
        #
        # Note: We can't use hasSelection() here, as that's always
        # true in caret mode.
        if not self.selection_enabled:
            self._widget.page().currentFrame().evaluateJavaScript(
                utils.read_file("javascript/position_caret.js")
            )