Code Insights: Fix bad live setting fetching

Created by: vovakulikov

Closes https://github.com/sourcegraph/sourcegraph/issues/22558

Context

Our customers noticed that sometimes the live preview chart in the creation UI doesn't - it doesn't show the live preview chart but instead renders some weird error about the GQL fragment.

It turned out that in some cases when the first request about live chart data processing returns nothing we won't stop further search fetching with no data error but instead run empty GQL request (by empty I mean request with empty variables object). So because of that we've got this error.