It would be nice to get a clearer error message when there's a missing argument to a subgraph or an op (maybe only within a subgraph). Currently I get an error like this about a missing config:

DagsterInvalidConfigError: Error in config when building job 'battery_data_job_local' from graph 'battery_data_graph'
    Error 1: Missing required config entry "ops" at the root. Sample config for missing entry: {'ops': {'data_pipe_graph_nessie_anode': {'ops': {'sanitation_graph': {'ops': {'_sanitize_task': {'inputs': {'algorithms': '<unknown>'}}}}}}, 'data_pipe_graph_nessie_cathode': {'ops': {'sanitation_graph': {'ops': {'_sanitize_task': {'inputs': {'algorithms': '<unknown>'}}}}}}, 'data_pipe_graph_nessie_full_cell': {'ops': {'sanitation_graph': {'ops': {'_sanitize_task': {'inputs': {'algorithms': '<unknown>'}}}}}}, 'data_pipe_graph_sasquatch_anode': {'ops': {'sanitation_graph': {'ops': {'_sanitize_task': {'inputs': {'algorithms': '<unknown>'}}}}}}, 'data_pipe_graph_sasquatch_cathode': {'ops': {'sanitation_graph': {'ops': {'_sanitize_task': {'inputs': {'algorithms': '<unknown>'}}}}}}, 'data_pipe_graph_sasquatch_reactor': {'ops': {'sanitation_graph': {'ops': {'_sanitize_task': {'inputs': {'algorithms': '<unknown>'}}}}}}}}

In m case I'm generating a number of instances of the subgraph, so it's very verbose. My preference would be to get an error that said (a) there is a parameter to your graph/op function that is never passed in and (b) it could be a config value or an argument.