Trying to return value from a GUIDE GUI causes struct error

I want to make a simple popup window for my main Gui, which would have a few input fields and an Apply button. I start the filterDialog() popup in my main code, and attempt to return something when it exits. I was following the instructions I found here

https://ch.mathworks.com/matlabcentral/answers/147242-collecting-user-inputs-with-multiple-gui-windows

I am getting an error

Struct contents reference from a non-struct array object.

Error in filterDialog>filterDialog_OutputFcn (line 74)
varargout{1} = handles.output;

---------------------------

function varargout = filterDialog(varargin)
% FILTERDIALOG MATLAB code for filterDialog.fig
%      FILTERDIALOG, by itself, creates a new FILTERDIALOG or raises the existing
%      singleton*.
%
%      H = FILTERDIALOG returns the handle to a new FILTERDIALOG or the handle to
%      the existing singleton*.
%
%      FILTERDIALOG('CALLBACK',hObject,eventData,handles,...) calls the local
%      function named CALLBACK in FILTERDIALOG.M with the given input arguments.
%
%      FILTERDIALOG('Property','Value',...) creates a new FILTERDIALOG or raises the
%      existing singleton*.  Starting from the left, property value pairs are
%      applied to the GUI before filterDialog_OpeningFcn gets called.  An
%      unrecognized property name or invalid value makes property application
%      stop.  All inputs are passed to filterDialog_OpeningFcn via varargin.
%
%      *See GUI Options on GUIDE's Tools menu.  Choose "GUI allows only one
%      instance to run (singleton)".
%
% See also: GUIDE, GUIDATA, GUIHANDLES

% Edit the above text to modify the response to help filterDialog

% Last Modified by GUIDE v2.5 08-Mar-2018 14:14:43

% Begin initialization code - DO NOT EDIT
gui_Singleton = 1;
gui_State = struct('gui_Name',       mfilename, ...
                   'gui_Singleton',  gui_Singleton, ...
                   'gui_OpeningFcn', @filterDialog_OpeningFcn, ...
                   'gui_OutputFcn',  @filterDialog_OutputFcn, ...
                   'gui_LayoutFcn',  [] , ...
                   'gui_Callback',   []);
if nargin && ischar(varargin{1})
    gui_State.gui_Callback = str2func(varargin{1});
end

if nargout
    [varargout{1:nargout}] = gui_mainfcn(gui_State, varargin{:});
else
    gui_mainfcn(gui_State, varargin{:});
end
% End initialization code - DO NOT EDIT

% --- Executes just before filterDialog is made visible.
function filterDialog_OpeningFcn(hObject, eventdata, handles, varargin)
% This function has no output args, see OutputFcn.
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
% varargin   command line arguments to filterDialog (see VARARGIN)

% Choose default command line output for filterDialog
handles.output = "SomeExampleOutput";

% Update handles structure
guidata(hObject, handles);

% UIWAIT makes filterDialog wait for user response (see UIRESUME)
uiwait(handles.figure1);

% --- Outputs from this function are returned to the command line.
function varargout = filterDialog_OutputFcn(hObject, eventdata, handles) 
% varargout  cell array for returning output args (see VARARGOUT);
% hObject    handle to figure
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Get default command line output from handles structure
varargout{1} = handles.output;

% The figure can be deleted now
delete(handles.figure1);

function figure1_CloseRequestFcn(hObject, eventdata, handles)

if isequal(get(hObject,'waitstatus'),'waiting')
    uiresume(hObject);
else
    delete(hObject);
end

% --- Executes on button press in filterApplyButton.
function filterApplyButton_Callback(hObject, eventdata, handles)
% hObject    handle to filterApplyButton (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

[Aleksejs Fomins]

Note: If I comment out

uiwait(handles.figure1);

and

delete(handles.figure1);

the error goes away, but the result is returned immediately, not waiting for my input

[Adam]

Is that the entire code?

[Aleksejs Fomins]

Almost. There are a few buttons and inputs on the form that do nothing and have automatically generated Callback functions. I did not touch them, so I deleted the callback functions from the above code not to clutter the minimal example with unrelated stuff. Also, I call the form from the main program via

result = filterDialog()
disp(result)

[Adam]

I can't see anything obviously wrong. The setup is the same as I have used for some of my GUIs that work as expected. Try putting breakpoints in the CloseRequestFcn and in the OutputFcn to see what is actually happening.

It seems like the GUI is being deleted before the OutputFcn so that the handles struct no longer exists, but I don't see why that would be.

The only difference in my examples that I see is that I use handles.figure1 rather than hObject in my closeRequestFcn, but I would have thought they should be the same thing there.

[Aleksejs Fomins]

Yep, tried changing to handles.figure1 in closeRequestFcn, result is the same :(

[Adam]

Can you attach the .fig and .m files? I can't really take a look otherwise since it is GUIDE code and I'd have to recreate the UI which may end up slightly different to what you have.

[Aleksejs Fomins]

Here you go. Thanks for taking your time :)

[Adam]

Try the attached files. To be honest I'm not sure what was wrong, but the CloseRequestFcn was not being called. All I did was go into GUIDE and right click the figure and select CloseRequestFcn from the View Callbacks and it then took me to the function you had already written so it seemed to think it was linked correctly. After that, however, it now works for me where it didn't before. Sometimes callbacks can get into this kind of state where they are not properly linked to the controls, I'm not sure what causes it, but doing what I did generally sets it straight again.

[Aleksejs Fomins]

You are my hero Adam!!! You deserve a cookie