🐛 gracefully handle errors when items missing in underlying metadata store

[tom-webber]

Describe the bug.

It's possible to query for objects that don't exist on the DataHub instance (due to differences between environments), which currently returns an error. This should be handled rather than returning an error as it causes confusion during development. It's unlikely that such searches would be possible to encounter in the production environment.

To Reproduce

KeyError for properties["name"] when filtering for Databases (containers) on the dev DataHub instance (prior to databases being added / implemented).

Expected Behaviour

A search with 0 entries because none are present on the instance should return 0 results, rather than a key error.

Additional context

No response

[murdo-moj]

There's now a switch in the search method of the datahub client to return an empty SearchResponse when the total results returned from DataHub is 0

[murdo-moj]

As part of the refactor we added 404 responses when a table/database/chart urn isn't found #265

[MatMoore]

• The 404 response is working as expected on the details page
• I've added a partial to render a (hopefully) helpful message in the event that search returns no results Tidy empty search results page #320

The copy may need to be improved later, but this allows us to handle this case without blowing up and without rendering unnecessary parts of the page like pagination