Error when zoom in

when zoom in before and in middle of gap section of Centaur sample

In develop branch there's error => when the plotting widget has no data

Traceback (most recent call last):
  File "/Users/ldam/anaconda3/envs/sohpyside6/lib/python3.8/site-packages/matplotlib/cbook/__init__.py", line 314, in process
    func(*args, **kwargs)
  File "/Users/ldam/Documents/GIT/sohview/sohstationviewer1/sohstationviewer/view/plotting/state_of_health_widget.py", line 36, in on_button_press_event
    return super().on_button_press_event(event)
  File "/Users/ldam/Documents/GIT/sohview/sohstationviewer1/sohstationviewer/view/plotting/plotting_widget/plotting_widget.py", line 472, in on_button_press_event
    w.on_shift_click(xdata)
  File "/Users/ldam/Documents/GIT/sohview/sohstationviewer1/sohstationviewer/view/plotting/plotting_widget/plotting_widget.py", line 533, in on_shift_click
    self.ruler.set_visible(False)
AttributeError: 'NoneType' object has no attribute 'set_visible'

In !266 (merged) there's additional error => happen when zoom in part of mass position that have data. Ex: 5244.sdr

Traceback (most recent call last):
  File "/Users/ldam/Documents/GIT/sohview/sohstationviewer1/sohstationviewer/view/plotting/plotting_widget/plotting_widget.py", line 540, in <lambda>
    QTimer.singleShot(1, lambda: self.zoom_bw_markers(xdata))
  File "/Users/ldam/Documents/GIT/sohview/sohstationviewer1/sohstationviewer/view/plotting/plotting_widget/plotting_widget.py", line 327, in zoom_bw_markers
    self.set_lim()
  File "/Users/ldam/Documents/GIT/sohview/sohstationviewer1/sohstationviewer/view/plotting/plotting_widget/plotting_widget.py", line 667, in set_lim
    ret = get_total_miny_maxy(x, y, self.min_x, self.max_x)
  File "/Users/ldam/Documents/GIT/sohview/sohstationviewer1/sohstationviewer/view/plotting/plotting_widget/plotting_widget_helper.py", line 53, in get_total_miny_maxy
    new_min_y = min(new_y)
ValueError: min() arg is an empty sequence