fix(appstore): Return an empty array in case of fail

Signed-off-by: Git'Fellow <12234510+solracsf@users.noreply.github.com>

lib/private/App/AppStore/Fetcher/AppFetcher.php

@@ -153,6 +153,9 @@ class AppFetcher extends Fetcher {
 		$allowPreReleases = $allowUnstable || $this->getChannel() === 'beta' || $this->getChannel() === 'daily' || $this->getChannel() === 'git';
 
 		$apps = parent::get($allowPreReleases);
+		if (empty($apps)) {
+			return [];
+		}
 		$allowList = $this->config->getSystemValue('appsallowlist');
 
 		// If the admin specified a allow list, filter apps from the appstore