gstlal-ugly/bin/gstlal_ll_dq: fix assertion error when theres no range history data
This should fix:
Traceback (most recent call last):
File "/usr/lib64/python3.6/site-packages/gstlal/stream.py", line 231, in sample_handler
func(buf)
File "/usr/bin/gstlal_ll_dq", line 137, in on_buffer
agg_sink.store_columns(measurement, data[route], aggregate="max")
File "/usr/lib/python3.6/site-packages/ligo/scald/io/influx.py", line 313, in store_columns
reduced_idx, reduced_time, reduced_key_column = core.reduce_data(time, columns[column_key], aggfunc, dt=1)
File "/usr/lib/python3.6/site-packages/ligo/scald/io/core.py", line 64, in reduce_data
assert len(yarr) == len(xarr), 'x and y arrays are not equal'
AssertionError: x and y arrays are not equal
This error comes up when trying to write data to influx before there is a spectrum message, so there is no range history data. In that case the time deque and data deque have different lengths and scald breaks.