I can't formatState of TextColumn having value null

TextColumn::make('last_contacted')->date('M d')->label('Last Attempt')->sortable()->formatStateUsing(function($state){
                    if($state != null){
                        info($state);
                    }
                    else{
                        info('hello');
                    }
                }),

TextColumn::make('last_contacted')->date('M d')->label('Last Attempt')->sortable()->formatStateUsing(function($state){
                    if($state != null){
                        info($state);
                    }
                    else{
                        info('hello');
                    }
                }),