Installation via conda (init cache directory)

[AugustinMortier]

I have lustre mounted in root but only read access. After installation of v0.7.0 using

conda install -c nordicesmhub -c conda-forge pyaerocom

I get the following error when trying to import pyaerocom:

>>> import pyaerocom as pya
Init data paths for lustre
0.0041120052337646484 s
Failed to access CACHEDIR: PermissionError(13, 'Permission denied')Deactivating caching
Failed to access CACHEDIR: PermissionError(13, 'Permission denied')Deactivating caching
Failed to access CACHEDIR: PermissionError(13, 'Permission denied')Deactivating caching
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/augustinm/miniconda3/lib/python3.6/site-packages/pyaerocom/__init__.py", line 93, in <module>
    from . import analysis
  File "/home/augustinm/miniconda3/lib/python3.6/site-packages/pyaerocom/analysis.py", line 24, in <module>
    from pyaerocom.io import ReadUngridded, ReadGridded
  File "/home/augustinm/miniconda3/lib/python3.6/site-packages/pyaerocom/io/__init__.py", line 74, in <module>
    from .readungridded import ReadUngridded
  File "/home/augustinm/miniconda3/lib/python3.6/site-packages/pyaerocom/io/readungridded.py", line 54, in <module>
    class ReadUngridded(object):
  File "/home/augustinm/miniconda3/lib/python3.6/site-packages/pyaerocom/io/readungridded.py", line 68, in ReadUngridded
    _DONOTCACHEFILE = os.path.join(const.OBSDATACACHEDIR, 'DONOTCACHE')
  File "/home/augustinm/miniconda3/lib/python3.6/posixpath.py", line 80, in join
    a = os.fspath(a)
TypeError: expected str, bytes or os.PathLike object, not NoneType