small change in kernelcreation to allow absolut access only kernels on GPU

pystencils/gpucuda/kernelcreation.py

@@ -45,12 +45,14 @@ def create_cuda_kernel(assignments: Union[AssignmentCollection, NodeCollection],
         num_buffer_accesses += sum(1 for access in eq.atoms(Field.Access) if FieldType.is_buffer(access.field))
 
     common_shape = get_common_shape(fields_without_buffers)
-
     if iteration_slice is None:
         # determine iteration slice from ghost layers
         if ghost_layers is None:
             # determine required number of ghost layers from field access
-            required_ghost_layers = max([fa.required_ghost_layers for fa in field_accesses])
+            if len(field_accesses) == 0:
+                required_ghost_layers = 0
+            else:
+                required_ghost_layers = max([fa.required_ghost_layers for fa in field_accesses])
             ghost_layers = [(required_ghost_layers, required_ghost_layers)] * len(common_shape)
         iteration_slice = []
         if isinstance(ghost_layers, int):