Error when running coupled.py example

[agoncalvescoel]

When I try to run the coupled.py example, I have the following error

(MYFIPYENV) anacoelho@HYHNB053:~/fipy$ FIPY_VIEWER=matplotlib python examples/diffusion/coupled.py
QStandardPaths: wrong permissions on runtime directory /run/user/1000/, 0755 instead of 0700
/home/anacoelho/miniconda3/envs/MYFIPYENV/lib/python3.11/site-packages/fipy/viewers/matplotlibViewer/__init__.py:122: UserWarning: Matplotlib1DViewer efficiency is improved by setting the 'datamax' and 'datamin' keys
  return Matplotlib1DViewer(vars=vars, title=title, axes=axes, **kwlimits)
Uncaught exception:
Traceback (most recent call last):
  File "/home/anacoelho/fipy/examples/diffusion/coupled.py", line 125, in <module>
    exec(fipy.tests.doctestPlus._getScript())
  File "<string>", line 103, in <module>
  File "/home/anacoelho/miniconda3/envs/MYFIPYENV/lib/python3.11/site-packages/fipy/viewers/__init__.py", line 131, in Viewer
    raise ImportError("Failed to import a viewer: %s" % str(errors))
ImportError: Failed to import a viewer: ['matplotlib: can only concatenate str (not "int") to str']

[guyer]

Thank you for reporting. This is a duplicate of #961. I'll prioritize pushing out a fix.