interact has issues when passing a Mesh instead of image

When using `stackview.interact` with something that is no image, it crashes:

```
import numpy as np
import stackview

surface = nppas._vedo_stanford_bunny()
mesh = nppas.to_vedo_mesh(surface)

def do_show(mesh, zoom:float = np.exp(1), azimuth:float = 0, elevation:float = 0, roll:float = 0):
from vedo import Plotter
plt = Plotter(offscreen=True, size=[600,400], N=2)
plt.show(mesh, zoom=np.log(zoom), azimuth=azimuth, elevation=elevation, roll=roll)
return plt.screenshot(asarray=True)

stackview.interact(do_show, mesh, continuous_update=True)
```

Error:
```
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
Cell In[5], line 10
7 plt.show(mesh, zoom=np.log(zoom), azimuth=azimuth, elevation=elevation, roll=roll)
8 return plt.screenshot(asarray=True)
---> 10 stackview.interact(do_show, mesh, continuous_update=True)

File ~\mambaforge\envs\bio39\lib\site-packages\stackview\_interact.py:108, in interact(func, image, continuous_update, context, zoom_factor, zoom_spline_order, viewer, *args, **kwargs)
106 viewer_was_none = viewer is None
107 if viewer_was_none:
--> 108 viewer = _SliceViewer(image, zoom_factor=zoom_factor, zoom_spline_order=zoom_spline_order)
109 viewer.slice_slider.continuous_update=continuous_update
110 command_label = ipywidgets.Label(value=func_name + "()")

File ~\mambaforge\envs\bio39\lib\site-packages\stackview\_slice_viewer.py:21, in _SliceViewer.__init__(self, image, slice_number, axis, display_width, display_height, continuous_update, slider_text, zoom_factor, zoom_spline_order)
18 self.image = image
20 if slice_number is None:
---> 21 slice_number = int(image.shape[axis] / 2)
23 if len(self.image.shape) == 3 and self.image.shape[-1] != 3:
24 self.view = ImageWidget(np.take(image, slice_number, axis=axis), zoom_factor=zoom_factor, zoom_spline_order=zoom_spline_order)

AttributeError: 'Mesh' object has no attribute 'shape'
```