cody: lvlgraph: consistency check for graphnode

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@40433 4005530d-fff6-0310-9dd1-cebe43e6787f
LCL, dblookup, prevent SIGSEGV if ListLinkDataset is closed, from Julio Jiménez Borreguero

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@40434 4005530d-fff6-0310-9dd1-cebe43e6787f