pyeccodes is not API compatible with eccodes.

[pmav99]

When you install pyeccodes without installing eccodes, you get the following exception

$ python -m cfgrib selfcheck
Traceback (most recent call last):
  File "/home/panos/.conda/envs/poseidon/lib/python3.8/runpy.py", line 185, in _run_module_as_main
    mod_name, mod_spec, code = _get_module_details(mod_name, _Error)
  File "/home/panos/.conda/envs/poseidon/lib/python3.8/runpy.py", line 144, in _get_module_details
    return _get_module_details(pkg_main_name, error)
  File "/home/panos/.conda/envs/poseidon/lib/python3.8/runpy.py", line 111, in _get_module_details
    __import__(pkg_name)
  File "/home/panos/Prog/pyPoseidon/.venv/lib/python3.8/site-packages/cfgrib/__init__.py", line 19, in <module>
    from .cfmessage import CfMessage
  File "/home/panos/Prog/pyPoseidon/.venv/lib/python3.8/site-packages/cfgrib/cfmessage.py", line 29, in <module>
    from . import messages
  File "/home/panos/Prog/pyPoseidon/.venv/lib/python3.8/site-packages/cfgrib/messages.py", line 54, in <module>
    eccodes.codes_grib_multi_support_off()
AttributeError: module 'pyeccodes.compat' has no attribute 'codes_grib_multi_support_off'

I believe that the easiest way to resolve this is to remove the try:except ImportError block and just raise the ImportError