Merge pull request #24 from MAIF/feature/warn_when_cfgrib_not_installed

ImportError with clear help when cfgrib not installed

src/meteole/forecast.py

@@ -6,6 +6,7 @@
 import tempfile
 from abc import ABC, abstractmethod
 from functools import reduce
+from importlib.util import find_spec
 from typing import Any
 
 import pandas as pd
@@ -15,6 +16,12 @@
 from meteole.clients import BaseClient
 from meteole.errors import MissingDataError
 
+if find_spec("cfgrib") is None:
+    raise ImportError(
+        "The 'cfgrib' module is required to read Arome and Arpege GRIB files. Please install it using:\n\n"
+        "  conda install -c conda-forge cfgrib\n\n"
+    )
+
 logger = logging.getLogger(__name__)