bug in zooming at overlaping area

The error shows clearer in using lim to zoom.

Traceback (most recent call last):
  File "/Users/ldam/Documents/GIT/soh_gar/sohstationviewer/sohstationviewer/view/plotting/plotting_widget/plotting_widget.py", line 453, in <lambda>
    QTimer.singleShot(1, lambda: self.zoom_bw_markers(xdata))
  File "/Users/ldam/Documents/GIT/soh_gar/sohstationviewer/sohstationviewer/view/plotting/plotting_widget/plotting_widget.py", line 285, in zoom_bw_markers
    self.set_lim()
  File "/Users/ldam/Documents/GIT/soh_gar/sohstationviewer/sohstationviewer/view/plotting/plotting_widget/plotting_widget.py", line 600, in set_lim
    ret = get_total_miny_maxy(x, y, self.min_x, self.max_x)
  File "/Users/ldam/Documents/GIT/soh_gar/sohstationviewer/sohstationviewer/view/util/functions.py", line 264, in get_total_miny_maxy
    new_min_y = min(new_y)
ValueError: min() arg is an empty sequence

To reproduce: experiment Q330 5244, zoom in waveform data