Fix draft assets error

[rosemcc]

Description

This PR contains a fix for a bug where pages that are published with a link to a draft asset or a link to a page with a draft asset would not load, and would be directed to /error/500. The error is an internal server error from the graphql API and is classed as a 'Query execution error'. Because data is still returned for the page in question, the page should still load, albeit with some missing data (the draft asset will show as null in the returned data), and the error should be ignored. This would be very similar to how we currently handle draft linked entries - they are essentially ignored, and the page is still rendered, minus the draft entries.

Solution

In AppModule in te graphql client onError handler, there is now a check for the draft asset error: graphQLErrors[0].message.includes('Query execution error. Link from entry')
If this error occurs then it is ignored and the page will still load with whatever data has been returned from the server. Because the app already handles null values the UI should be still rendered correctly.

Screenshots

N/A

Testing

Manual testing for the following cases:

• Draft asset is a banner image - in this case cards fall back to the default image, and page is rendered correctly but with no banner image
• Draft asset is in the rich text body - page loads, image/document is not shown
• Draft asset is in an expandable page part - page loads, image is not shown
• Draft asset is a funding page application document - page loads, doc is not shown
• Draft asset is the Home page banner image - page loads with a grey background in the banner instead of the image
• Draft asset is an activity page image - page loads but with a white background section where the image would normally be

Have the changes been checked in the following browsers?

N/A

[Trombach]

LGTM!