site-kit-wp: Enhance presentation of internal server errors in widgets with Site Kit specific guidance

Bug Description

For errors that come from WordPress core, which we output in the Site Kit widgets consider including any HTML markup. At present errors such as the below can appear, which don’t contain a link and have unusual formatting, with no space between the sentences.

"There has been a critical error on this website.Learn more about troubleshooting WordPress"

Video of experience

Steps to reproduce

1. Set up Site Kit
2. Open a new tab and navigate to the Site Kit dashboard
3. Click on your user profile icon in the header and select “Manage Sites” from the dropdown
4. Click the button to “Remove access” for the site you are using
5. Close the browser tab - do not click “Back” to go back to your site as this will trigger a disconnect
6. Wait 1 hour for the cached content to expire
7. Revisit your Site Kit dashboard

Additional Context

• We did decide to strip html comments previously. See https://github.com/google/site-kit-wp/issues/4169

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Acceptance criteria

• The ReportError component should be updated to display a custom error message for errors with a code of internal_server_error:
  • The content of the new error message should be: There was a critical error on this website while fetching data.
• The ReportError component should be updated to display a custom error message for errors with a code of invalid_json:
  • The content of the new error message should be: The server provided an invalid response.
• This logic to alter the error messages conditionally should be implemented in a reusable way so that it does not only work in the ReportError component, but it should also be used in the custom error notices used in the PageSpeed Insights widget (see LabReportMetrics and FieldReportMetrics components).
  • Those two components should be altered to also have the message accompanied by the “Retry” button and “Get help” link (using similar markup and copy as this combination of button/link uses elsewhere in the plugin already).
• In both cases, it should be ensured that the usual “Retry” button and following “Get help” link are present. This may already be the case based on current logic, but should be double checked, and added if not already present.

Implementation Brief

• Create a new function, getReportErrorMessage (or any proper name), which accepts an error object and returns the message according to the AC when the error.code is internal_server_error and invalid_json, falling back to error.message.
• Use this new function to determine the error messages within the ReportError, LabReportMetrics, and FieldReportMetrics components.
• Create a new reusable component, ReportErrorActions (or any proper name).
  • It takes moduleSlug (string) and error (object|array<object>) as arguments.
  • Extract the Request access and Retry buttons and the Get help link from the ReportError component, including the handleRetry callback and associated code, and render them in the new component.
• Update the ReportError, LabReportMetrics, and FieldReportMetrics components to render the new ReportErrorActions component.

Test Coverage

• Add test cases for the getReportErrorMessage utility function.
• Add test cases for the ReportErrorActions component.
• Add stories for the ReportErrorActions component.
• In assets/js/components/ReportError.stories.js, add stories for the internal_server_error and invalid_json errors.
• In stories/module-pagespeed-insights-components.stories.js, add error stories for the LabReportMetrics and FieldReportMetrics components.

QA Brief

• Check the steps to reproduce section to reproduce the bug.
• Ensure that the wording in the error message is now as per the AC.
• Stories can be verified here:
  • https://google.github.io/site-kit-wp/storybook/pull/6322/?path=/story/modules-pagespeed-insights-widgets-dashboardpagespeedwidget--error
  • https://google.github.io/site-kit-wp/storybook/pull/6322/?path=/story/components-reporterror--report-error-with-custom-internal-server-error-message
  • https://google.github.io/site-kit-wp/storybook/pull/6322/?path=/story/components-reporterror--report-error-with-custom-invalid-json-message

QA Eng Brief

• Simulate the internal_server_error and invalid_json error messages for a specific module, for e.g for the ‘GET:report’ Analytics endpoint. Ensure the messages are displayed as per the AC.

Changelog entry

• Improve error messages when encountering an internal server error in WordPress.