Bug when selected time out of available range in RT130

Ex: RT130-sample 1970-01-01 to 2011-11-03

Some in RT130-sample can't be read due to error: Traceback (most recent call last):
  File "/Users/ldam/Documents/GIT/sohview/sohstationviewer1/sohstationviewer/model/data_loader.py", line 88, in run
    data_object.__init__(
  File "/Users/ldam/Documents/GIT/sohview/sohstationviewer1/sohstationviewer/model/reftek_data/reftek.py", line 88, in __init__
    self.processing_data()
  File "/Users/ldam/Documents/GIT/sohview/sohstationviewer1/sohstationviewer/model/reftek_data/reftek.py", line 103, in processing_data
    self.finalize_data()
  File "/Users/ldam/Documents/GIT/sohview/sohstationviewer1/sohstationviewer/model/reftek_data/reftek.py", line 126, in finalize_data
    self.combine_all_data()
  File "/Users/ldam/Documents/GIT/sohview/sohstationviewer1/sohstationviewer/model/general_data/general_data.py", line 363, in combine_all_data
    combine_data(key, self.waveform_data, self.gap_minimum)
  File "/Users/ldam/Documents/GIT/sohview/sohstationviewer1/sohstationviewer/model/general_data/general_data_helper.py", line 157, in combine_data
    channel['startTmEpoch'] = min([tr['startTmEpoch']
ValueError: min() arg is an empty sequence