Setting a value to bool property

class.Isoverhung=_presenter.Getthevalue();

in above line of code either class object may be null or _presenter may be null. if both not null, then there can be null object in Getthevalue method!
But we can't say exactly where, which object is null or what you can do with your given information, You can put break point before above line and check line by line which is causing this exception and then you can find solution for that. check below previous questions on codeproject for more information
[C#] NullReference Exception was unhandled[^]

try this ternarry operator

bool outValue;
class.Isoverhung=bool.TryParse(_presenter.Getthevalue(),out outValue)?outValue:default(bool);

class.Isoverhung=_presenter.Getthevalue();
class.Isoverhung=0/1; //We should pass 1 or 0 to bool