How to Create Custom Error Types from Go

[blluv]

Hi, I'm trying to create custom error types from Go.

Looking at the implementation of NewTypeError:

func (r *Runtime) NewTypeError(args ...interface{}) *Object {
	msg := ""
	if len(args) > 0 {
		f, _ := args[0].(string)
		msg = fmt.Sprintf(f, args[1:]...)
	}
	return r.builtin_new(r.getTypeError(), []Value{newStringValue(msg)})
}

func (r *Runtime) getTypeError() *Object {
	ret := r.global.TypeError
	if ret == nil {
		ret = &Object{runtime: r}
		r.global.TypeError = ret
		r.newNativeFuncConstructProto(ret, r.builtin_Error, "TypeError", r.createErrorPrototype(stringTypeError, ret), r.getError(), 1)
	}
	return ret
}

It seems like I could create a custom error type using builtin_new and newNativeFuncConstructProto, similar to how TypeError is constructed. However, both of these methods are unexported, so I can't access them from outside the package.

Is there a recommended way to define custom error constructors (like MyCustomError), or would this require changes to the Goja ?

Thanks!