No error message when index was not found

[ronja-ui]

Description
If a user tries to do a search with a wrong index name, there won't be any error message or other visual cue that they used a non-existing index name. Instead, a table with "No data available in table", which could be interpret as the index just don't have any data but it's existing.

Some kind of message such as "The searched index doesn't exist. Please check the index's name for typoes." or similar would be much better.