Flag summary exits with error code 1

[Athanaseus]

Running the current release version on a GMRT data set results in an error when producing the flag summary.
This is due to the two fake GMRT antennas that throw a NaN in 'output/diagnostic_plots/Original-cal-flag-flagging-summary-0.json' due to no available data (See full traceback below).

Original issue caracal-pipeline/caracal#1422

# Traceback (most recent call last):
#   File "/stimela_mount/code/run.py", line 35, in <module>
#     flag_stats.plot_statistics(**args)
#   File "/usr/local/lib/python3.6/dist-packages/MSUtils/flag_stats.py", line 423, in plot_statistics
#     _plot_flag_stats(**flag_data, outfile=htmlfile)
#   File "/usr/local/lib/python3.6/dist-packages/MSUtils/flag_stats.py", line 417, in _plot_flag_stats
#     row(plot_list[1], plot_list[0])))
#   File "/usr/local/lib/python3.6/dist-packages/bokeh/io/saving.py", line 86, in save
#     _save_helper(obj, filename, resources, title, template, theme)
#   File "/usr/local/lib/python3.6/dist-packages/bokeh/io/saving.py", line 148, in _save_helper
#     html = file_html(obj, resources, title=title, template=template, theme=theme)
#   File "/usr/local/lib/python3.6/dist-packages/bokeh/embed/standalone.py", line 304, in file_html
#     (docs_json, render_items) = standalone_docs_json_and_render_items(models_seq, suppress_callback_warning=suppress_callback_warning)
#   File "/usr/local/lib/python3.6/dist-packages/bokeh/embed/util.py", line 294, in standalone_docs_json_and_render_items
#     docs_json[docid] = doc.to_json()
#   File "/usr/local/lib/python3.6/dist-packages/bokeh/document/document.py", line 902, in to_json
#     doc_json = self.to_json_string()
#   File "/usr/local/lib/python3.6/dist-packages/bokeh/document/document.py", line 959, in to_json_string
#     return serialize_json(json, indent=indent)
#   File "/usr/local/lib/python3.6/dist-packages/bokeh/core/json_encoder.py", line 166, in serialize_json
#     return json.dumps(obj, cls=BokehJSONEncoder, allow_nan=False, indent=indent, separators=separators, sort_keys=True, **kwargs)
#   File "/usr/lib/python3.6/json/__init__.py", line 238, in dumps
#     **kw).encode(obj)
#   File "/usr/lib/python3.6/json/encoder.py", line 199, in encode
#     chunks = self.iterencode(o, _one_shot=True)
#   File "/usr/lib/python3.6/json/encoder.py", line 257, in iterencode
#     return _iterencode(o, 0)
# ValueError: Out of range float values are not JSON compliant
2022-05-18 10:55:16 CARACal.Stimela.flag-summary-ms0 ERROR: cd /home/peter/Current_Reduction/J1150_00_caracal/.stimela_workdir-16528640819505663 && singularity returns error code 1
2022-05-18 10:55:16 CARACal.Stimela.flag-summary-ms0 ERROR: job failed at 2022-05-18 10:55:16.196315 after 0:00:05.003909
2022-05-18 10:55:16 CARACal ERROR: Job 'flag-summary-ms0:: Flagging summary  ms=Original-cal.ms' failed: cd /home/peter/Current_Reduction/J1150_00_caracal/.stimela_workdir-16528640819505663 && singularity returns error code 1 [PipelineException]
2022-05-18 10:55:16 CARACal INFO:   More information can be found in the logfile at /home/peter/Current_Reduction/J1150_00_caracal/output/logs-20220518-105320/log-caracal.txt
2022-05-18 10:55:16 CARACal INFO: exiting with error code 1