Fix: Don't break when passing in params for "Search Query"

[bobdenotter]

No description provided.

[I-Valchev]

@bobdenotter I wonder if this will break it if you'd like to seach for something that is empty?

[bobdenotter]

I think we need to differentiate between two types of "breaking" here:

1. Malformed input causing Bolt to show an error page (which it should never do)
2. Malformed input causing incorrect results (which is unavoidable, because we don't control what's being input)

This PR fixes one two instances of the former, where I managed to get an exception screen.

I did some monkey-testing on searching for non-existing Fieldnames and the like. Searching for 'empty' values treats it like that parameter isn't there, so I think that's OK.

[I-Valchev]

@bobdenotter right I see! Let's roll with this 👍