Fatal Error when trying to view "themes" dashboard page.

Hello,

When trying to view the themes dashboard page is get the "something went wrong" error. This has occurred after I deleted the files in the theme cache folder.

294: $addons = [];
295: foreach ($index as $addonDirName => $addonDirPath) {
296: try {
297: $addon = $this->lookupSingleCachedAddon($addonDirName, $type);
*298: $addons[$addon->getKey()] = $addon;
299: } catch (\Exception $ex) {
300: trigger_error("The $type in $subdir is invalid and will be skipped.", E_USER_WARNING);
301: // Clear the addon out of the index.
302: $this->deleteSingleIndexKey($type, $addonDirName);

*this is the line producing the error.

Backtrace

[/home/u330615656/public_html/discuss/library/core/class.thememanager.php:86] Vanilla\AddonManager->lookupAllByType();
[/home/u330615656/public_html/discuss/applications/dashboard/controllers/class.settingscontroller.php:1828] Gdn_ThemeManager->availableThemes();
[/home/u330615656/public_html/discuss/library/core/class.dispatcher.php:845] SettingsController->themes();
[/home/u330615656/public_html/discuss/library/core/class.dispatcher.php:274] Gdn_Dispatcher->dispatchController();
[/home/u330615656/public_html/discuss/index.php:29] Gdn_Dispatcher->dispatch();

I have just installed vanilla forums today and have not yet made any other changes.

I would be very thankful for your advice