curses: Check if value is provided for ngraph
curses: Check if value is provided for ngraph

Fixes: CID 49001
Signed-off-by: Thomas Graf <17c2d8920621522552b392f72d8fdb4d1e866b44@suug.ch>

Chocobo1/bmon,tklauser/bmon,Chocobo1/bmon,tklauser/bmon