re: `exposure_schema_validity`: please help out my stupid brain assume you have _exposure_a_ and _exposure_b_, both relying only on _model_x_. this yields the warnings

Warning - missing node property for the exposure: exposure_a which not the only exposure depending on model_x, We're not able to verify the column level dependencies of this exposure

Warning - missing node property for the exposure: exposure_b which not the only exposure depending on model_x, We're not able to verify the column level dependencies of this exposure

unlike when a exposure relies on multiple models, why would elementary need the

node

here? what is undefined?