Rounding of GRIB grid

src/climetlab/sources/constants.py

@@ -297,7 +297,7 @@ def find_numbers(source_or_dataset):
  source_or_dataset, "unique_values"
  ), f"{source_or_dataset} (type '{type(source_or_dataset).__name__}') is not a proper source or dataset"
 
- return source_or_dataset.unique_values("number", patches={"number": {None: 0}})["number"]
+ return source_or_dataset.unique_values("number", patches={"number": {None: 0}}).get("number", 0)
 
  def find_dates(source_or_dataset):
  if "date" not in self.request and "time" in self.request: