`soil_awc`: crashes when the requested extent is outside the data extent

This kind of call triggers an error in the console:

https://api.g-eau.fr/soil_awc?with_coarse_elements=true&L93X_min=498799&L93X_max=521566&L93Y_min=1036200&L93Y_max=1058893

radis-api-1 | <simpleError in .local(x, y, ...): extents do not overlap>