backend returns incorrect binWidthRange for single data range #255

This bug was found when addressing VEuPathDB/web-monorepo#959 (closed but has detailed information) and VEuPathDB/web-monorepo#961 (replacing 959): this is possibly address by VEuPathDB/web-monorepo#964.

As shown in the screenshots (please see below), if frontend passes binWidth: undefined to backend, then backend returns correct value, binWidth: 1. However, binWidthRange is incorrect, { min: 0.1, max: 0 }, which causes error in Viz control: red border in the second screenshot which means that it has error and the value cannot be changed. Also bin slider shows incorrect range as well. Danielle confirmed that this is a bug at plot.data.

An example test case: qa.vectorbase.org; STUDY: Geolocation visualizations of field-based studies; EDA histogram Viz; Filter: Species -> Aedes; Main variable: count of traps.