Object is not iterable error when result set is empty

[albertocalderari]

Bug Report

A select query returning no results triggers an exception rather than just an empty result.
This behaviour does not appear when using a different data source which leads to an empty series object (i.e. prometheus)

Expected Behaviour

The chart should display "No data" or no display anything

Actual Behaviour

An Object is not iterable exception is thrown

Steps to Reproduce the Problem

1. create a new panel
2. using the BQ source create a query that returns no results:
   i.e. ```SELECT
   $__timeGroupAlias(TimeStamp,1h),
   count(*) AS errors
   from table
   where 1=2

## Specifications

- Version: 2.0.1
- Platform: MacOs 10.15.7
- Grafana Version: Grafana v7.2.1 (72a6c64532)

[ofir5300]

Hi @albertocalderari ,
Thanks for sharing this great input, we will probably fix it in the coming release (2.0.2)

[albertocalderari]

NP, looking forward to the new release!