diff --git a/src/AssetFactory.php b/src/AssetFactory.php
index 1135f98..c7ba657 100644
--- a/src/AssetFactory.php
+++ b/src/AssetFactory.php
@@ -14,8 +14,8 @@
 namespace Inpsyde\Assets;
 
 use Inpsyde\Assets\Exception\InvalidArgumentException;
-use Inpsyde\Assets\Loader\PhpFileLoader;
 use Inpsyde\Assets\Loader\ArrayLoader;
+use Inpsyde\Assets\Loader\PhpFileLoader;
 
 /**
  * Class AssetFactory
@@ -90,7 +90,7 @@ public static function create(array $config): Asset
             }
 
             $inFooter = $config['inFooter'] ?? true;
-            $inFooter
+            $inFooter === true
                 ? $asset->isInFooter()
                 : $asset->isInHeader();
 
diff --git a/src/AssetManager.php b/src/AssetManager.php
index 44ebc0a..84c161d 100644
--- a/src/AssetManager.php
+++ b/src/AssetManager.php
@@ -19,7 +19,6 @@
 use Inpsyde\Assets\Handler\ScriptHandler;
 use Inpsyde\Assets\Handler\StyleHandler;
 use Inpsyde\Assets\Util\AssetHookResolver;
-use Inpsyde\Assets\Asset;
 
 final class AssetManager
 {
@@ -114,7 +113,7 @@ public function register(Asset $asset, Asset ...$assets): AssetManager
 
         foreach ($assets as $asset) {
             $handle = $asset->handle();
-            if ($handle) {
+            if ($handle !== '') {
                 $this->assets->attach($asset, [$handle, get_class($asset)]);
             }
         }
@@ -258,7 +257,7 @@ private function loopCurrentHookAssets(string $currentHook, bool $process): arra
 
         /** @var int|null $locationId */
         $locationId = Asset::HOOK_TO_LOCATION[$currentHook] ?? null;
-        if (!$locationId) {
+        if (is_null($locationId)) {
             return [];
         }
 
@@ -314,7 +313,10 @@ private function ensureSetup(): void
          *
          * @psalm-suppress PossiblyNullArgument
          */
-        if (!$lastHook && did_action($lastHook) && !doing_action($lastHook)) {
+        if (
+            (is_null($lastHook) || $lastHook === '') &&
+            did_action($lastHook) && !doing_action($lastHook)
+        ) {
             $this->assets = new \SplObjectStorage();
 
             return;
diff --git a/src/Caching/IgnoreSitegroundCache.php b/src/Caching/IgnoreSitegroundCache.php
index ed06be1..2b63029 100644
--- a/src/Caching/IgnoreSitegroundCache.php
+++ b/src/Caching/IgnoreSitegroundCache.php
@@ -24,12 +24,14 @@ public function apply(array $handles): void
          * Ignore Javascript
          */
         add_filter('sgo_js_minify_exclude', static function (array $scripts) use ($handles) {
+            assert(is_array($handles[Script::class]));
             return array_merge($scripts, $handles[Script::class]);
         });
 
         add_filter(
             'sgo_javascript_combine_exclude',
             static function (array $scripts) use ($handles) {
+                assert(is_array($handles[Script::class]));
                 return array_merge($scripts, $handles[Script::class]);
             }
         );
@@ -38,9 +40,11 @@ static function (array $scripts) use ($handles) {
          * Ignore Styles
          */
         add_filter('sgo_css_minify_exclude', static function (array $styles) use ($handles) {
+            assert(is_array($handles[Style::class]));
             return array_merge($styles, $handles[Style::class]);
         });
         add_filter('sgo_css_combine_exclude', static function (array $styles) use ($handles) {
+            assert(is_array($handles[Style::class]));
             return array_merge($styles, $handles[Style::class]);
         });
     }
diff --git a/src/Caching/IgnoreW3TotalCache.php b/src/Caching/IgnoreW3TotalCache.php
index 25073a3..186f2a8 100644
--- a/src/Caching/IgnoreW3TotalCache.php
+++ b/src/Caching/IgnoreW3TotalCache.php
@@ -26,7 +26,7 @@ public function apply(array $handles): void
          */
         add_filter('w3tc_minify_js_do_tag_minification', static function (bool $doMinification, string $scriptTag) use ($handles) {
             foreach ($handles[Script::class] as $handle) {
-                if (strpos($scriptTag, $handle) !== false) {
+                if (strpos($scriptTag, (string)$handle) !== false) {
                     return false;
                 }
             }
@@ -38,7 +38,7 @@ public function apply(array $handles): void
          */
         add_filter('w3tc_minify_css_do_tag_minification', static function (bool $doMinification, string $scriptTag) use ($handles) {
             foreach ($handles[Style::class] as $handle) {
-                if (strpos($scriptTag, $handle) !== false) {
+                if (strpos($scriptTag, (string)$handle) !== false) {
                     return false;
                 }
             }
diff --git a/src/Loader/AbstractWebpackLoader.php b/src/Loader/AbstractWebpackLoader.php
index a8f9655..840ad76 100644
--- a/src/Loader/AbstractWebpackLoader.php
+++ b/src/Loader/AbstractWebpackLoader.php
@@ -68,10 +68,13 @@ public function load($resource): array
                 )
             );
         }
+        $json = @file_get_contents($resource);
 
-        $data = @file_get_contents($resource)
-            ?: ''; // phpcs:ignore
-        $data = json_decode($data, true);
+        if ($json === false) {
+            $json = '';
+        }
+
+        $data = json_decode($json, true);
         $errorCode = json_last_error();
         if (0 < $errorCode) {
             throw new InvalidResourceException(
@@ -183,23 +186,23 @@ protected function sanitizeFileName(string $file): string
      */
     protected function resolveLocation(string $fileName): int
     {
-        if (stristr($fileName, '-backend')) {
+        if (stristr($fileName, '-backend') !== false) {
             return Asset::BACKEND;
         }
 
-        if (stristr($fileName, '-block')) {
+        if (stristr($fileName, '-block') !== false) {
             return Asset::BLOCK_EDITOR_ASSETS;
         }
 
-        if (stristr($fileName, '-login')) {
+        if (stristr($fileName, '-login') !== false) {
             return Asset::LOGIN;
         }
 
-        if (stristr($fileName, '-customizer-preview')) {
+        if (stristr($fileName, '-customizer-preview') !== false) {
             return Asset::CUSTOMIZER_PREVIEW;
         }
 
-        if (stristr($fileName, '-customizer')) {
+        if (stristr($fileName, '-customizer') !== false) {
             return Asset::CUSTOMIZER;
         }
 
diff --git a/src/OutputFilter/AsyncStyleOutputFilter.php b/src/OutputFilter/AsyncStyleOutputFilter.php
index 98cc1ef..753d846 100644
--- a/src/OutputFilter/AsyncStyleOutputFilter.php
+++ b/src/OutputFilter/AsyncStyleOutputFilter.php
@@ -39,7 +39,7 @@ public function __invoke(string $html, Asset $asset): string
     {
         $url = $asset->url();
         $version = $asset->version();
-        if ($version) {
+        if ($version !== null && $version !== '') {
             $url = add_query_arg('ver', $version, $url);
         }
 
diff --git a/src/OutputFilter/InlineAssetOutputFilter.php b/src/OutputFilter/InlineAssetOutputFilter.php
index 63bffd7..edc85e8 100644
--- a/src/OutputFilter/InlineAssetOutputFilter.php
+++ b/src/OutputFilter/InlineAssetOutputFilter.php
@@ -35,7 +35,7 @@ public function __invoke(string $html, Asset $asset): string
         }
 
         $content = @file_get_contents($filePath);
-        if (! $content) {
+        if ($content === false) {
             return $html;
         }
 
diff --git a/src/Script.php b/src/Script.php
index 44a8b8b..168d9b4 100644
--- a/src/Script.php
+++ b/src/Script.php
@@ -13,7 +13,6 @@
 
 namespace Inpsyde\Assets;
 
-use Inpsyde\Assets\Handler\AssetHandler;
 use Inpsyde\Assets\Handler\ScriptHandler;
 
 class Script extends BaseAsset implements Asset
@@ -260,7 +259,7 @@ protected function resolveDependencyExtractionPlugin(): bool
         $version = $data['version'] ?? null;
 
         $this->withDependencies(...$dependencies);
-        if (!$this->version && $version) {
+        if (is_null($this->version) && !is_null($version)) {
             $this->withVersion($version);
         }
 
diff --git a/src/Style.php b/src/Style.php
index 82ee727..e9f888b 100644
--- a/src/Style.php
+++ b/src/Style.php
@@ -13,7 +13,6 @@
 
 namespace Inpsyde\Assets;
 
-use Inpsyde\Assets\Handler\AssetHandler;
 use Inpsyde\Assets\Handler\StyleHandler;
 use Inpsyde\Assets\OutputFilter\AsyncStyleOutputFilter;
 
@@ -73,7 +72,7 @@ public function inlineStyles(): ?array
      */
     public function withInlineStyles(string $inline): Style
     {
-        if (!$this->inlineStyles) {
+        if (!is_array($this->inlineStyles)) {
             $this->inlineStyles = [];
         }
 
diff --git a/src/Util/AssetPathResolver.php b/src/Util/AssetPathResolver.php
index 7b49551..1b40f9a 100644
--- a/src/Util/AssetPathResolver.php
+++ b/src/Util/AssetPathResolver.php
@@ -41,8 +41,8 @@ public static function resolveForVendorUrl(string $normalizedUrl): ?string
         // Now let's see if it's inside vendor.
         // This is problematic, this is why vendor assets should be "published".
 
-        $fullVendorPath = wp_normalize_path(realpath(__DIR__ . '/../../../'));
-        $abspath = wp_normalize_path(ABSPATH);
+        $fullVendorPath = wp_normalize_path((string)realpath(__DIR__ . '/../../../'));
+        $abspath = wp_normalize_path((string)ABSPATH);
         $abspathParent = dirname($abspath);
 
         $relativeVendorPath = null;
@@ -52,12 +52,12 @@ public static function resolveForVendorUrl(string $normalizedUrl): ?string
             $relativeVendorPath = substr($normalizedUrl, strlen($abspathParent));
         }
 
-        if (!$relativeVendorPath) {
+        if ($relativeVendorPath !== null && $relativeVendorPath !== '') {
             // vendor is not inside ABSPATH, nor inside its parent
             return null;
         }
 
-        $relativeVendorPath = trim($relativeVendorPath, '/');
+        $relativeVendorPath = trim((string)$relativeVendorPath, '/');
 
         // problematic, as said above: we are assuming vendor URL, but this assumption isn't safe
         $vendorUrl = network_site_url("/{$relativeVendorPath}");
@@ -90,7 +90,7 @@ public static function resolveForThemeUrl(string $normalizedUrl): ?string
             $relativeThemeUrl = substr($normalizedUrl, strlen($themeUrl));
         }
 
-        return $relativeThemeUrl
+        return $relativeThemeUrl !== null && $relativeThemeUrl !== ''
             ? trailingslashit($base) . trim($relativeThemeUrl, '/')
             : null;
     }
@@ -113,8 +113,8 @@ public static function resolveForPluginUrl(string $normalizedUrl): ?string
             $basePath = WPMU_PLUGIN_DIR;
             $relativePluginUrl = substr($normalizedUrl, strlen($muPluginsUrl));
         }
-
-        return $relativePluginUrl
+        assert(is_string($basePath));
+        return $relativePluginUrl !== null && $relativePluginUrl !== ''
             ? trailingslashit(wp_normalize_path($basePath)) . trim($relativePluginUrl, '/')
             : null;
     }