fix: set correct API error codes in exception classes

- InvalidApiKeyException: code 900
- SigningHashVerificationException: code 901
- MissingAccessRightsException: code 902
- ForbiddenIpException: code 903
- Fix nullable type hints for $previous parameter

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: cl77

src/Exception/ForbiddenIpException.php

@@ -6,7 +6,7 @@
 
 class ForbiddenIpException extends Exception
 {
-    public function __construct($message = 'The server IP is not included in the list of permitted IP addresses', $code = 0, Exception $previous = null)
+    public function __construct($message = 'The server IP is not included in the list of permitted IP addresses', $code = 903, ?Exception $previous = null)
     {
         parent::__construct($message, $code, $previous);
     }

src/Exception/InvalidApiKeyException.php

@@ -6,7 +6,7 @@
 
 class InvalidApiKeyException extends Exception
 {
-    public function __construct($message = 'The given API Key is invalid', $code = 0, Exception $previous = null)
+    public function __construct($message = 'The given API Key is invalid', $code = 900, ?Exception $previous = null)
     {
         parent::__construct($message, $code, $previous);
     }

src/Exception/MissingAccessRightsException.php

@@ -6,7 +6,7 @@
 
 class MissingAccessRightsException extends Exception
 {
-    public function __construct($message = 'The API key does not have access rights to this endpoint.', $code = 0, Exception $previous = null)
+    public function __construct($message = 'The API key does not have access rights to this endpoint.', $code = 902, ?Exception $previous = null)
     {
         parent::__construct($message, $code, $previous);
     }

src/Exception/SigningHashVerificationException.php

@@ -6,7 +6,7 @@
 
 class SigningHashVerificationException extends Exception
 {
-    public function __construct($message = 'Verification of the signing hash failed', $code = 0, Exception $previous = null)
+    public function __construct($message = 'Verification of the signing hash failed', $code = 901, ?Exception $previous = null)
     {
         parent::__construct($message, $code, $previous);
     }

src/Exception/UnexpectedApiResponseException.php

@@ -6,7 +6,7 @@
 
 class UnexpectedApiResponseException extends Exception
 {
-    public function __construct($message, $code = 0, Exception $previous = null)
+    public function __construct($message, $code = 0, ?Exception $previous = null)
     {
         parent::__construct($message, $code, $previous);
     }