Matlab Guide-created GUI local function calls

I have a rather complex GUI that was created with GUIDE and sort of grew to monstrous proportions. I am now calling my local functions within the GUI from other scripts and from the command line. I have noticed that when calling a local function, the gui_mainfcn.m chokes if the first passed argument is a character array.

For example:

I would like to call the function myFunction which is housed in myGUI.m

I can call the function successfully by using

outputs = myGUI('myFunction', argument1, argument2, argument3...);

as long as argument1 is not a character array.

The error traces to line 78 in gui_mainfcn.m where ishghandle is called on the second argument which ends up blowing up specifically if it is a character array.

Is there a way around this issue, or should I just avoid character arrays as the first argument in any of my local gui functions? Maybe it could be fixed in future versions of MATLAB?