SeamAE does not have a related CSeamLandCrv.
The Seam Active Entity (SeamIntersect_AE, SeamOffset_AE, SeamProjection_AE, SeamByTable_AE) is missing its relationship to the Seam Landing Curve. A curve needed to be defined.
What You Should Do
Ask your database administrator to back up the model.
Run the Clean Database custom command to delete the object.