diff --git a/index.php b/index.php
index 68e0b788..4c4acef2 100644
--- a/index.php
+++ b/index.php
@@ -151,11 +151,9 @@ public function getCurrentVersion() {
 
 	/**
 	 * Returns currently used release channel
-	 *
-	 * @return string
 	 */
-	private function getCurrentReleaseChannel() {
-		return !is_null($this->getConfigOption('updater.release.channel')) ? $this->getConfigOption('updater.release.channel') : 'stable';
+	private function getCurrentReleaseChannel(): string {
+		return (string)($this->getConfigOption('updater.release.channel') ?? 'stable');
 	}
 
 	/**
@@ -206,10 +204,9 @@ public function updateAvailable() {
 	/**
 	 * Returns the specified config options
 	 *
-	 * @param string $key
 	 * @return mixed|null Null if the entry is not found
 	 */
-	public function getConfigOption($key) {
+	public function getConfigOption(string $key) {
 		return isset($this->configValues[$key]) ? $this->configValues[$key] : null;
 	}
 
@@ -1078,7 +1075,7 @@ public function endStep($step) {
 	}
 
 	/**
-	 * @return string
+	 * @return array
 	 * @throws \Exception
 	 */
 	public function currentStep() {