objectPicker edge case behaviours
Two cases to be considered for the object picker:
1. If an object picker has an initial value which is not found in a (successful) Ajax call, that value should be removed, as it is likely that saving it would error on a foreign key restraint
2. If the object picker's Ajax call fails for any reason, the initial value should be retained, not blanked out - which removes any previously saved values in the event of an Ajax error.