fix style

src/AccessToken.php

@@ -38,6 +38,7 @@
 use SimpleJWT\JWT as SimpleJWT;
 use SimpleJWT\Keys\KeyFactory;
 use SimpleJWT\Keys\KeySet;
+use TypeError;
 use UnexpectedValueException;
 
 /**
@@ -399,6 +400,10 @@ private function checkAndInitializePhpsec()
         }
     }
 
+    /**
+     * @return string
+     * @throws TypeError If the key cannot be initialized to a string.
+     */
     private function loadPhpsecPublicKey(string $modulus, string $exponent): string
     {
         if (class_exists(RSA::class) && class_exists(BigInteger2::class)) {
@@ -411,7 +416,11 @@ private function loadPhpsecPublicKey(string $modulus, string $exponent): string
                     $exponent
                 ]), 256),
             ]);
-            return $key->getPublicKey();
+            $formattedPublicKey = $key->getPublicKey();
+            if (is_string($formattedPublicKey)) {
+                return $formattedPublicKey;
+            }
+            throw new TypeError('Failed to initialize the key');
         }
         $key = PublicKeyLoader::load([
             'n' => new BigInteger3($this->callJwtStatic('urlsafeB64Decode', [
@@ -421,7 +430,12 @@ private function loadPhpsecPublicKey(string $modulus, string $exponent): string
                 $exponent
             ]), 256),
         ]);
-        return $key->toString('PKCS8');
+        // Ensure the key is correctly initialized
+        $formattedPublicKey = $key->toString('PKCS8');
+        if (is_string($formattedPublicKey)) {
+            return $formattedPublicKey;
+        }
+        throw new TypeError('Failed to initialize the key');
     }
 
     /**