[BUG] Search Comparison Tool should report query execution errors

[smacrakis]

What is the bug?

Search Comparison Tool doesn't report an error when the DSL query results in an error.

How can one reproduce the bug?

Enter {"this":"is a bogus query"} as Query 1. Hit Search.
This displays "No results" under Result 1.
Under Dev Tools, this reports a parsing exception.

What is the expected behavior?

Result 1 should show that there was an error. This could be something as simple as "Query error" or it could show the JSON error report. No need to get fancier than that (e.g., to make it human-friendly).

What is your host/environment?

n/a

Do you have any screenshots?

Not needed.

Do you have any additional context?