diff --git a/composer.json b/composer.json
index 2885a8c..36deb19 100644
--- a/composer.json
+++ b/composer.json
@@ -32,7 +32,7 @@
 		"test": "php phpunit.phar",
 		"test-setup": "[ ! -f phpunit.phar ] && wget https://phar.phpunit.de/phpunit-8.5.2.phar && mv phpunit-8.5.2.phar phpunit.phar || true",
 		"test-coverage" : "php phpunit.phar --log-junit tmp/coverage/unitreport.xml --coverage-html tmp/coverage --coverage-clover tmp/coverage/coverage.xml",
-		"stan": "phpstan analyse -c tests/phpstan.neon -l 5 src/",
+		"stan": "phpstan analyse -c tests/phpstan.neon src/",
 		"stan-setup": "cp composer.json composer.backup && composer require --dev phpstan/phpstan:^0.12 && mv composer.backup composer.json",
 		"cs-check": "phpcs -p -v --standard=vendor/fig-r/psr2r-sniffer/PSR2R/ruleset.xml --extensions=php src/ tests/ config/",
 		"cs-fix": "phpcbf -p --standard=vendor/fig-r/psr2r-sniffer/PSR2R/ruleset.xml --extensions=php src/ tests/ config/"
diff --git a/src/Controller/Component/CacheComponent.php b/src/Controller/Component/CacheComponent.php
index 46d6c46..020bf19 100644
--- a/src/Controller/Component/CacheComponent.php
+++ b/src/Controller/Component/CacheComponent.php
@@ -51,14 +51,13 @@ public function shutdown(EventInterface $event): void {
 		}
 		/** @var callable $when */
 		$when = $this->getConfig('when');
-		if ($when !== null && $when($event->getSubject()->getRequest()) !== true) {
+		/** @var \Cake\Controller\Controller $controller */
+		$controller = $event->getSubject();
+		if ($when !== null && $when($controller->getRequest()) !== true) {
 			return;
 		}
 
-		/** @var \Cake\Http\Response $response */
-		$response = $event->getSubject()->getResponse();
-
-		$content = (string)$response->getBody();
+		$content = (string)$controller->getResponse()->getBody();
 		if (!$content) {
 			return;
 		}
@@ -112,7 +111,7 @@ protected function _writeContent(string $content, $duration) {
 		$url = str_replace($this->getController()->getRequest()->getAttribute('base'), '', $url);
 		$cacheKey = CacheKey::generate($url, $this->getConfig('prefix'));
 
-		$ext = $this->getController()->getResponse()->mapType($this->getController()->getResponse()->getType());
+		$ext = (string)$this->getController()->getResponse()->mapType($this->getController()->getResponse()->getType());
 		$content = $this->_compress($content, $ext);
 
 		$content = '<!--cachetime:' . $cacheTime . ';ext:' . $ext . '-->' . $content;
diff --git a/src/Routing/Middleware/CacheMiddleware.php b/src/Routing/Middleware/CacheMiddleware.php
index 2a2a682..39aea9d 100644
--- a/src/Routing/Middleware/CacheMiddleware.php
+++ b/src/Routing/Middleware/CacheMiddleware.php
@@ -124,7 +124,7 @@ protected function getContent(string $url, string $cacheKey) {
 				return null;
 			}
 
-			return file_get_contents($file);
+			return file_get_contents($file) ?: null;
 		}
 
 		return Cache::read($cacheKey, $engine) ?: null;
@@ -229,7 +229,7 @@ protected function _deliverCacheFile(ServerRequest $request, Response $response,
 
 		$modifiedTime = $cacheStart ?: time();
 		if (!$cacheEnd) {
-			$cacheEnd = $this->getConfig('cacheTime');
+			$cacheEnd = $this->getConfig('cacheTime', '+1 hour');
 		}
 
 		$response = $response->withCache($modifiedTime, $cacheEnd);
diff --git a/src/Shell/CacheShell.php b/src/Shell/CacheShell.php
index f5fac85..e1bb20d 100644
--- a/src/Shell/CacheShell.php
+++ b/src/Shell/CacheShell.php
@@ -52,6 +52,7 @@ protected function fileStatus($url) {
 			$count = iterator_count($fi);
 			$this->out($count . ' cache files found.');
 			if ($this->param('verbose')) {
+				/** @var \SplFileInfo $f */
 				foreach ($fi as $f) {
 					$this->out(' - ' . $f->getFileName());
 				}
diff --git a/src/Utility/FileCache.php b/src/Utility/FileCache.php
index 9fcfb43..26a5d3c 100644
--- a/src/Utility/FileCache.php
+++ b/src/Utility/FileCache.php
@@ -52,7 +52,7 @@ public function getContent($url) {
 				return null;
 			}
 
-			return file_get_contents($file);
+			return file_get_contents($file) ?: null;
 		}
 
 		return Cache::read($cacheKey, $engine) ?: null;
diff --git a/tests/phpstan.neon b/tests/phpstan.neon
index 6bdca8e..8afb997 100644
--- a/tests/phpstan.neon
+++ b/tests/phpstan.neon
@@ -1,6 +1,11 @@
 parameters:
-	autoload_files:
+	level: 7
+
+	checkMissingIterableValueType: false
+
+	bootstrapFiles:
 		- %rootDir%/../../../tests/bootstrap.php
 		- %rootDir%/../../../tests/shim.php
 	ignoreErrors:
 		- '#Parameter \#1 \$function of function call_user_func expects callable\(\): mixed, mixed given.#'
+		- '#Cannot cast array\|string\|null to string#'