FPGDBMIDebugger: fix function result uninitialized

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@44162 4005530d-fff6-0310-9dd1-cebe43e6787f
FPDebug: handle nil in class results

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@44163 4005530d-fff6-0310-9dd1-cebe43e6787f