Node has Parent context does not explicitly check if the field exists.

What steps does it take to reproduce the issue?

Add a context condition that gets triggered on Node has Parent.
In Field that contains reference to parents select field_member_of
Create a new content type.
Add a content reference field with some other field name than field_member_of (field_node_reference, for example)
Add new content of this type.
Make sure the content reference field has a value.
This results in a WSOD.

What happens? WSOD

What did you expect to happen? The content gets created

Which version of Islandora are you using? 2.0

Fix https://github.com/Islandora/islandora/blob/3902cce0ac7525aa209e56f198d5059f4c42e09a/src/Plugin/Condition/NodeHasParent.php#L141

Should check whether field exists.

Disabled check should happen before the evaluation of context conditions.

Screenshots:

Islandora / islandora