Protect: Fixed undefined credentials property warning

[dkmyta]

Fixes #
When viewing the Protect UI with no plan, we receive an undefined property warning because we are checking the status report for a property that only exists when the Scan API is used.

Changes proposed in this Pull Request:

• Adds an isset() check to the corresponding stdClass::$credentials property upon status report generation.

Other information:

• Have you written new tests for your changes, if applicable?
• Have you checked the E2E test CI results, and verified that your changes do not break them?

Jetpack product discussion

• 1201069996155224-as-1203359421438051

Does this pull request change what data or activity we track or use?

• No

Testing instructions:

• Start up a Jurassic Ninja instance with the Jetpack Beta plugin installed, with detailed error logging enabled
• Using the Beta plugin install add/scan-in-protect branch of Protect
• Start with the Free version of the plugin and proceed to the Protect admin page and allow the initial report to generate
• View the initial report and refer to the site debug.log file to verify the following warning is output:

PHP Warning:  Undefined property: stdClass::$credentials in /usr/local/src/jetpack-monorepo/projects/plugins/protect/src/class-credentials.php

• Proceed to the Beta plugin admin screen and update the Protect plugin to use the current branch
• Visit the Protect admin screen and refer once again to your debug.log to ensure the error is no additional error entry

[github-actions]

Thank you for your PR!

When contributing to Jetpack, we have a few suggestions that can help us test and review your patch:

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The e2e test report can be found here. Please note that it can take a few minutes after the e2e tests checks are complete for the report to be available.

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🔴 Action required: Please add missing changelog entries for the following projects: projects/plugins/protect

Use the Jetpack CLI tool to generate changelog entries by running the following command: jetpack changelog add.
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Protect plugin:

• Next scheduled release: December 6, 2022.
• Scheduled code freeze: November 28, 2022.

[nateweller]

Perfect!