Property existence static validations

[unreadablewxy]

A problem has been brought to my attention. Once a config becomes sufficiently complicated, some static validation makes sense to catch potential runtime errors.

• It is not hard to scan path formats to determine the property requirements of a store.
• Produced properties are already parsed from hoppers
• We also know the names of all properties during reoffering
• All that is needed is to run a quick comparison between source & store to see if the source eclipses the store.