diff --git a/src/Encryption.php b/src/Encryption.php
index b1e0ed7..3903045 100644
--- a/src/Encryption.php
+++ b/src/Encryption.php
@@ -36,11 +36,12 @@ public static function padPayload(string $payload, int $maxLengthToPad, string $
 
         if ($contentEncoding === "aesgcm") {
             return pack('n*', $padLen).str_pad($payload, $padLen + $payloadLen, chr(0), STR_PAD_LEFT);
-        } elseif ($contentEncoding === "aes128gcm") {
+        }
+        if ($contentEncoding === "aes128gcm") {
             return str_pad($payload.chr(2), $padLen + $payloadLen, chr(0), STR_PAD_RIGHT);
-        } else {
-            throw new \ErrorException("This content encoding is not supported");
         }
+
+        throw new \ErrorException("This content encoding is not supported");
     }
 
     /**
@@ -63,7 +64,7 @@ public static function encrypt(string $payload, string $userPublicKey, string $u
     }
 
     /**
-     * @throws \ErrorException
+     * @throws \RuntimeException
      */
     public static function deterministicEncrypt(string $payload, string $userPublicKey, string $userAuthToken, string $contentEncoding, array $localKeyObject, string $salt): array
     {
@@ -88,7 +89,7 @@ public static function deterministicEncrypt(string $payload, string $userPublicK
             ]);
         }
         if (!$localPublicKey) {
-            throw new \ErrorException('Failed to convert local public key from hexadecimal to binary');
+            throw new \RuntimeException('Failed to convert local public key from hexadecimal to binary.');
         }
 
         // get user public key object
@@ -225,7 +226,9 @@ private static function createInfo(string $type, ?string $context, string $conte
             }
 
             return 'Content-Encoding: '.$type.chr(0).'P-256'.$context;
-        } elseif ($contentEncoding === "aes128gcm") {
+        }
+
+        if ($contentEncoding === "aes128gcm") {
             return 'Content-Encoding: '.$type.chr(0);
         }
 
@@ -299,23 +302,22 @@ private static function createLocalKeyObjectUsingOpenSSL(): array
     }
 
     /**
-     * @throws \ErrorException
+     * @throws \ValueError
      */
     private static function getIKM(string $userAuthToken, string $userPublicKey, string $localPublicKey, string $sharedSecret, string $contentEncoding): string
     {
-        if (!empty($userAuthToken)) {
-            if ($contentEncoding === "aesgcm") {
-                $info = 'Content-Encoding: auth'.chr(0);
-            } elseif ($contentEncoding === "aes128gcm") {
-                $info = "WebPush: info".chr(0).$userPublicKey.$localPublicKey;
-            } else {
-                throw new \ErrorException("This content encoding is not supported");
-            }
-
-            return self::hkdf($userAuthToken, $sharedSecret, $info, 32);
+        if (empty($userAuthToken)) {
+            return $sharedSecret;
+        }
+        if($contentEncoding === "aesgcm") {
+            $info = 'Content-Encoding: auth'.chr(0);
+        } elseif($contentEncoding === "aes128gcm") {
+            $info = "WebPush: info".chr(0).$userPublicKey.$localPublicKey;
+        } else {
+            throw new \ValueError("This content encoding is not supported.");
         }
 
-        return $sharedSecret;
+        return self::hkdf($userAuthToken, $sharedSecret, $info, 32);
     }
 
     private static function calculateAgreementKey(JWK $private_key, JWK $public_key): string
@@ -325,7 +327,7 @@ private static function calculateAgreementKey(JWK $private_key, JWK $public_key)
 
         $result = openssl_pkey_derive($publicPem, $privatePem, 256);
         if ($result === false) {
-            throw new \Exception('Unable to compute the agreement key');
+            throw new \RuntimeException('Unable to compute the agreement key.');
         }
         return $result;
     }
diff --git a/src/Subscription.php b/src/Subscription.php
index b211ddf..bad3061 100644
--- a/src/Subscription.php
+++ b/src/Subscription.php
@@ -27,7 +27,7 @@ public function __construct(
     ) {
         if($publicKey || $authToken || $contentEncoding) {
             $supportedContentEncodings = ['aesgcm', 'aes128gcm'];
-            if ($contentEncoding && !in_array($contentEncoding, $supportedContentEncodings)) {
+            if ($contentEncoding && !in_array($contentEncoding, $supportedContentEncodings, true)) {
                 throw new \ErrorException('This content encoding ('.$contentEncoding.') is not supported.');
             }
             $this->contentEncoding = $contentEncoding ?: "aesgcm";
diff --git a/src/WebPush.php b/src/WebPush.php
index 3a94db4..ce363a9 100644
--- a/src/WebPush.php
+++ b/src/WebPush.php
@@ -133,7 +133,7 @@ public function sendOneNotification(SubscriptionInterface $subscription, ?string
      *
      * @param null|int $batchSize Defaults the value defined in defaultOptions during instantiation (which defaults to 1000).
      *
-     * @return \Generator|MessageSentReport[]
+     * @return \Generator
      * @throws \ErrorException
      */
     public function flush(?int $batchSize = null): \Generator
@@ -186,7 +186,7 @@ public function flush(?int $batchSize = null): \Generator
     }
 
     /**
-     * @throws \ErrorException
+     * @throws \ErrorException|\Random\RandomException
      */
     protected function prepare(array $notifications): array
     {
@@ -282,21 +282,24 @@ public function getAutomaticPadding(): int
     /**
      * @param bool|int $automaticPadding Max padding length
      *
-     * @throws \Exception
+     * @throws \ValueError
      */
     public function setAutomaticPadding(bool|int $automaticPadding): WebPush
     {
-        if ($automaticPadding > Encryption::MAX_PAYLOAD_LENGTH) {
-            throw new \Exception('Automatic padding is too large. Max is '.Encryption::MAX_PAYLOAD_LENGTH.'. Recommended max is '.Encryption::MAX_COMPATIBILITY_PAYLOAD_LENGTH.' for compatibility reasons (see README).');
-        } elseif ($automaticPadding < 0) {
-            throw new \Exception('Padding length should be positive or zero.');
-        } elseif ($automaticPadding === true) {
-            $this->automaticPadding = Encryption::MAX_COMPATIBILITY_PAYLOAD_LENGTH;
+        if ($automaticPadding === true) {
+            $automaticPadding = Encryption::MAX_COMPATIBILITY_PAYLOAD_LENGTH;
         } elseif ($automaticPadding === false) {
-            $this->automaticPadding = 0;
-        } else {
-            $this->automaticPadding = $automaticPadding;
+            $automaticPadding = 0;
+        }
+
+        if($automaticPadding > Encryption::MAX_PAYLOAD_LENGTH) {
+            throw new \ValueError('Automatic padding is too large. Max is '.Encryption::MAX_PAYLOAD_LENGTH.'. Recommended max is '.Encryption::MAX_COMPATIBILITY_PAYLOAD_LENGTH.' for compatibility reasons (see README).');
         }
+        if($automaticPadding < 0) {
+            throw new \ValueError('Padding length should be positive or zero.');
+        }
+
+        $this->automaticPadding = $automaticPadding;
 
         return $this;
     }
diff --git a/tests/PushServiceTest.php b/tests/PushServiceTest.php
index ef878cb..f4bc95d 100644
--- a/tests/PushServiceTest.php
+++ b/tests/PushServiceTest.php
@@ -119,7 +119,7 @@ protected function createClosureTest($browserId, $options): callable
             $messageIndex = 0;
 
             foreach ($supportedContentEncodings as $contentEncoding) {
-                if (!in_array($contentEncoding, ['aesgcm', 'aes128gcm'])) {
+                if (!in_array($contentEncoding, ['aesgcm', 'aes128gcm'], true)) {
                     $this->expectException(ErrorException::class);
                     $this->expectExceptionMessage('This content encoding ('.$contentEncoding.') is not supported.');
                     $this->markTestIncomplete('Unsupported content encoding: '.$contentEncoding);