Hi! I ran into an issue when scanning GEFS A files filtered for parameters having "depthBelowLandLayer" as the vertical coordinate.

"depthBelowLandLayer" typically represents slices between a "topLevel" surface and a "bottomLevel" surface.
For the current GEFS A files there is only one such slice at 0.0 m and 0.1 m.

When message_keys are read from the CFMessage at line 185

message_keys = set(m.message_grib_keys())

"level" is not explicitly included in message_keys although m["level"] still will evaluate to the "topLevel" value. Consequently, the vertical level will not be included due to not clearing the check at line 250

if "typeOfLevel" in message_keys and "level" in message_keys:
                name = m["typeOfLevel"]
                coordinates.append(name)
                data = np.array(m["level"], dtype=float)[()]

A quick and dirty fix would be to check for either "level" or "topLevel" in message_keys viz.

if "typeOfLevel" in message_keys and ("level" in message_keys or "topLevel" in message_keys):

I am however unsure if this misses some unfortunate edge case.