This worked in very old releases, but not more recent ones. I get the feeling it's related to this code here that is explicitly excluding custom errors for some reason.
An easy way to test this is to run the TI-Boy CE launcher without its data appvar present on the system (which is how I learned about this), or you could make a simple C program that throws a custom error.
Edit: Based on the comment, I assume this means the Stop token in a BASIC program throws a custom error. But I also notice that you set the custom error string to an empty string before running a program, so perhaps you just need to check whether the custom error string is also still empty.
This worked in very old releases, but not more recent ones. I get the feeling it's related to this code here that is explicitly excluding custom errors for some reason.
An easy way to test this is to run the TI-Boy CE launcher without its data appvar present on the system (which is how I learned about this), or you could make a simple C program that throws a custom error.
Edit: Based on the comment, I assume this means the Stop token in a BASIC program throws a custom error. But I also notice that you set the custom error string to an empty string before running a program, so perhaps you just need to check whether the custom error string is also still empty.