Add null response handling

[wscourge]

1. Update customer methods to accept both positional and array arguments.
2. Add null response check and dedicated exception.

[Copilot]

Pull request overview

This PR adds null response handling to the ChartMogul SDK and enhances customer attribute/tag methods to accept both array and positional arguments.

Key Changes:

• Added NetworkException for null response scenarios with validation in Client and Retry classes
• Updated customer methods (addTags, removeTags, addCustomAttributes, removeCustomAttributes, updateCustomAttributes) to accept both array and positional arguments while maintaining backward compatibility

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/Exceptions/NetworkException.php	New exception class for network-related failures
src/Http/Client.php	Added null response checks in send() and handleResponse() methods
src/Http/Retry.php	Added null result validation for both zero-retry and retry scenarios
src/Customer.php	Updated tag and custom attribute methods to support both array and positional arguments
tests/Unit/Http/ClientNullResponseTest.php	Tests for null response handling in Client
tests/Unit/Http/RetryNullHandlingTest.php	Tests for null response handling in Retry
tests/Unit/CustomerArrayAttributesTest.php	Comprehensive tests for new array argument support in customer methods

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 4 comments.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[swember]

any particular reason why it should be handled like that here? It just looks a little bit weird to allow $response to be null just to raise an exception if it's null.

[wscourge]

@swember as I understand this is the exact underlying issue: right now, we don't recognise null responses and it leads to timeouts. Raising an exception solves this.

I am not an PHP virtuoso though, and I'm very open to different suggestions.

[wscourge]

After consulting with @swember I have removed this check. I'll be looking into all API responses to make sure none of them return null.

@swember please take another look at the PR, I'd like to proceed with releasing the rest of changes.