fcl-db: sqldb: when TSQLQuery.FieldDefs.Update is called (is used by IDE Field editor for "Add fields ...") for closed (never prepared) dataset then Cursor is nil, and is passed to TSQLConnection.AddFieldDefs where AV can occurs.
So call Prepare before ...
Bug #25829

git-svn-id: http://svn.freepascal.org/svn/fpc/trunk@27021 3ad0048d-3df7-0310-abae-a5850022a9f2