Error when running Hotelling's Law example

[venzen]

Describe the bug
In Hotelling Law example, running app.py gives the following error:

ERROR:    Component react.component(__main__.SpaceDrawer) raised exception TypeError("'NoneType' object is not subscriptable")
Traceback (most recent call last):
  File "/data/mesa/venv/lib/python3.12/site-packages/reacton/core.py", line 1702, in _render
    root_element = el.component.f(*el.args, **el.kwargs)
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/data/mesa/mesa-examples/examples/hotelling_law/app.py", line 141, in SpaceDrawer
    rect_x = pos[0] + (i * width)
             ~~~^^^
TypeError: 'NoneType' object is not subscriptable

Expected behavior
According to the PNG file included with the example, agents should be positioned on a grid.

To Reproduce

$ cd mesa-examples/examples/hotelling_law/
$ git branch
* main
$ solara run app.py

Additional context

$ python --version
Python 3.12.11
$ python -c "import mesa; print(mesa.__version__)"
3.2.0
$ uname -a
Linux --- 5.15.0-139-generic #149-Ubuntu SMP Fri Apr 11 22:06:13 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux

[tpike3]

Thanks @venzen, we will have it look into it, more than likely you can fix by installing Mesa < 3.2 (i.e. 3.15). But we will give it a look.