Error message when compiling App: "Warning: A value of class "char" was indexed with no subscripts specified."

I have written a fairly long (>6000 lines) app. Can someone please explain what this error means, how to locate the offending code, and how to fix it? The full message is "Warning: A value of class "char" was indexed with no subscripts specified. Currently the result of this operation is the indexed value itself, but in a future release, it will be an error."

Thanks!

Answer 1

[Walter Roberson]

https://www.mathworks.com/matlabcentral/answers/406580-why-do-i-get-warning-a-value-of-class-matlab-internal-video-pluginmanager-was-indexed-with-no-s

But see the discussion at https://www.mathworks.com/matlabcentral/answers/390198-directly-accessing-a-method-of-a-returned-object-shadows-argument-list#answer_311539