Index key error when using fetch1('KEY')

[shenshan]

Bug Report

Description

When using fetch1('KEY') in datajoint 0.12.8, it gives this error when using fetch1('KEY'):

[dimitri-yatsenko]

This occurred when dj.config['fetch_format'] was set to "frame" to return Pandas dataframes. The fetch_format applies only to results of fetch not fetch1. But fetch1 calls fetch and did not handle the dataframe results correctly. The fix was to set format="array" when calling fetch from fetch1. Fixed in #878.