Very small map area can lead to "invalid value" error

[hholzgra]

This error got reported on several attempts to render a rather small area of around 20x20 to 30x30 meters:

Traceback (most recent call last):
  File "/home/maposmatic/maposmatic/scripts/render.py", line 523, in run
    output_count = renderer.render(config, self.job.layout,
  File "/home/maposmatic/ocitysmap/ocitysmap/__init__.py", line 792, in render
    self._render_one(config, tmpdir, renderer_cls,
  File "/home/maposmatic/ocitysmap/ocitysmap/__init__.py", line 921, in _render_one
    surface.finish()
cairo.Error: invalid value (typically too big) for the size of the input (surface, pattern, etc.)

See e.g.: https://print.get-map.org/maps/267097