Add catch

[lebogg]

By coincidence (docker-compose didn't use the latest engine image where listCatalogs got implemented), I came across an unwanted behavior if a page of the engine is not reachable. In this case, it was the apiUrl of listCatalogs :
https://github.com/clouditor/ui-next/blob/cb3fdee539b9c45a11d9d0ec83fde80b2adac677/src/lib/orchestrator.ts#L241-L255

The browser tries continuously to refresh the page while also doing auth every time. I played a round a little bit and a simple

.catch((message) => {
            return  null})

would do the trick.
Maybe wo could even change the throwError function to consider 404 Not Found not as an error, but I think that doesn't make sense.

What do you think @oxisto