Fix parsing member field in notification.removed_from_channel event

[nuno-vieira]

🔗 Issue Links

#2251

🎯 Goal

In the notification.removed_from_channel event, the user field is not present inside the member field, although the user_id is. This PR adds a fallback so that if the user is not present, we use the id from the user_id property.

The backend will change this meanwhile, and make sure the user field is always present. But since we don't have an ETA for this, it makes sense to add this fallback.

☑️ Contributor Checklist

• I have signed the Stream CLA (required)
• Changelog is updated with client-facing changes
• New code is covered by unit tests
• This change follows zero ⚠️ policy (required)
• Comparison screenshots added for visual changes
• Affected documentation updated (docusaurus, tutorial, CMS)

[martinmitrevski]

LGTM ✅

[sonarcloud]

SonarCloud Quality Gate failed.   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

97.1% Coverage
12.2% Duplication

[polqf]

The only comment I would add is that we should be using optionals instead of unwrapped values in tests

[nuno-vieira]

@polqf That will take some time to change. Besides that, most of the tests are performing against optional values, so if we just use the optional value on the actuals, there's a chance of having false positives, if both are nil