implement getError method

src/Client.php

@@ -85,24 +85,23 @@ class Client
         bool $json = true
     ): ?array
     {
-        $response = curl_exec(
+        if ($response = curl_exec($this->_curl))
-            $this->_curl
+        {
-        );
+            return $json ? json_decode($response, true) : $response;
+        }
+
+        return null;
+    }
 
-        $errorNumber = curl_errno(
+    public function getError(?int &$code = null): mixed
+    {
+        $code = curl_errno(
             $this->_curl
         );
 
-        $errorText = curl_error(
+        return curl_error(
             $this->_curl
         );
-
-        if ($response)
-        {
-            return $json ? json_decode($response, true) : $response;
-        }
-
-        return null;
     }
 
     public function getBlockCount(): ?int