Refresh positions of all draw points after deleting or moving - App designer

Following my last question (https://www.mathworks.com/matlabcentral/answers/1619365-extract-position-of-all-draw-points) I did an app designer GUI with two buttons and axes. The first one (LoadimageButton) is loading the pappers image and I can mark points until I press escape. The second button is printing out the point coordinates (PositionButton).

I have noticed that after pressing the two buttons I can move points in the axes and change their positions or delete them. The issue is that when I press the delete (in the context menu) I get this error after pressing the PositionButton:

Error using images.roi.Point/get
Invalid or deleted object.

Error in tempDrwPnt1/PositionButtonPushed (line 61)
positions = cell2mat(get(app.pointhandles, 'position'))

Error while evaluating Button PrivateButtonPushedFcn.

How can I refresh the app.pointhandles after deleting a point?

Code:

function LoadimageButtonPushed(app, event)
            imshow('peppers.png','Parent',app.ImageAxes); 
          
            userStopped = false; 
            app.pointhandles = gobjects(); 
                   while ~userStopped
                        roi = drawpoint(app.ImageAxes); 
                        if ~isvalid(roi) || isempty(roi.Position)
                            % End the loop
                            userStopped = true;
                        else
                            % store point object handle
                            app.pointhandles(end+1) = roi;
                        end
                   end 
            

            addlistener(roi,'MovingROI',@allevents);
            addlistener(roi,'ROIMoved',@allevents);
  
            app.pointhandles(1) = []; 
            
            function allevents(src,evt)
                evname = evt.EventName;
                switch(evname)
                    case{'MovingROI'}
                        disp(['ROI moving previous position: ' mat2str(evt.PreviousPosition)]);
                        disp(['ROI moving current position: ' mat2str(evt.CurrentPosition)]);
                    case{'ROIMoved'}
                        disp(['ROI moved previous position: ' mat2str(evt.PreviousPosition)]);
                        disp(['ROI moved current position: ' mat2str(evt.CurrentPosition)]);
                end
            end 
end


% Button pushed function: PositionButton
function PositionButtonPushed(app, event) 
positions = cell2mat(get(app.pointhandles, 'position'))
end

[Image Analyst]

I don't know. We can't reproduce because you didn't attach the .mlapp file.

Answer 1

[Image Analyst]

Not sure what's going on here:

app.pointhandles(1) = []; 
positions = cell2mat(get(app.pointhandles, 'position'))

How can you get the position property of pointhandles when you just set it to null? It throws an error. Why are you setting it to null?

[Ali razi]

Its to remove the the initial empty handle (

https://www.mathworks.com/matlabcentral/answers/1619365-extract-position-of-all-draw-points

)

[Ali razi]

I updated the question and the mlapp.