Scatter should not display hist or density if n points is low

[ecomodeller]

The calculation of density in each bin fails if the number of samples is too low.

[jsmariegaard]

Will give strange errors like this:

---

ValueError Traceback (most recent call last)
File c:\Users\jem\AppData\Local\mambaforge\lib\site-packages\matplotlib\pyplot.py:197, in _draw_all_if_interactive()
195 def _draw_all_if_interactive() -> None:
196 if matplotlib.is_interactive():
--> 197 draw_all()

File c:\Users\jem\AppData\Local\mambaforge\lib\site-packages\matplotlib_pylab_helpers.py:132, in Gcf.draw_all(cls, force)
130 for manager in cls.get_all_fig_managers():
131 if force or manager.canvas.figure.stale:
--> 132 manager.canvas.draw_idle()

File c:\Users\jem\AppData\Local\mambaforge\lib\site-packages\matplotlib\backend_bases.py:1893, in FigureCanvasBase.draw_idle(self, *args, **kwargs)
1891 if not self._is_idle_drawing:
1892 with self._idle_draw_cntx():
-> 1893 self.draw(*args, **kwargs)

File c:\Users\jem\AppData\Local\mambaforge\lib\site-packages\matplotlib\backends\backend_agg.py:388, in FigureCanvasAgg.draw(self)
385 # Acquire a lock on the shared font cache.
386 with (self.toolbar._wait_cursor_for_draw_cm() if self.toolbar
387 else nullcontext()):
--> 388 self.figure.draw(self.renderer)
389 # A GUI class may be need to update a window using this draw, so
390 # don't forget to call the superclass.
391 super().draw()
...
-> 1959 raise ValueError("minvalue must be less than or equal to maxvalue")
1960 elif vmin == vmax:
1961 result.fill(0)

ValueError: minvalue must be less than or equal to maxvalue