It depends on what you were hoping to achieve.
What part of the system you are working with.
Whether you were in combat at the time the error happened
And whether you set up your custom frame button to work in the secured environment ( if it's needed ).
For example:
This example for the OnClick command (
https://warcraft.wiki.gg/wiki/UIHANDLER_OnClick ) doesn't mention the need for a secured environment, so it should not error out like that.
So, depending on what the other 2 functions relate to and access could point to the reason why you are having this problem. Maybe seeing what those other functions do will help identify the cause.