It's probably the good fix but in the wrong place. If the error is further down the parsed object, this will fail. This should be in the very 1st if of the loop.

@Marsup Could you provide a failing example?

Just add some more nesting on a and cause a deeper error, like `a: "{b:{c:"string"}}". Your code basically only works if the error happens on the object being parsed, not inside.

@Marsup I tried this:

            const schema = {
                a: Joi.object({
                    b: Joi.object({
                        c: Joi.string()
                    })
                })
            };

            const input = {
                a: '{"b":{"d":"string"}}'
            };

            expect(() => {

                Joi.attempt(input, schema);
            }).to.throw(/\"d\" is not allowed/);
            done();

and that:

            const schema = {
                a: Joi.object({
                    b: Joi.object({
                        c: Joi.object({
                            d: Joi.string()
                        })
                    })
                })
            };

            const input = {
                a: '{"b":{"c":{"d":{}}}}'
            };

            expect(() => {

                Joi.attempt(input, schema);
            }).to.throw(/\"d\" must be a string/);
            done();

Both cases are not failing without any changes to the fix.

Sorry, I should have been more accurate, while this is fixing the failure, it's not fixing the issue. If you look at the error annotation, it's showing the list of errors correctly but can't pinpoint it on the input.

Eg. with your 2nd example :

ValidationError: {
  "a": "{\"b\":{\"c\":{\"d\":{}}}}" // There should be a [1] here or on the parsed object
}

[1] "d" must be a string

@Marsup I fixed the issue with the '_$miss$_forbiddenKey|1_$end$_' TypeError.
You are talking about an issue with error annotation.
I added a failing test case for the missing [1], but I don't know how to fix it yet.
Moving the typeof ref === 'string' check to the very 1st if of the loop doesn't help.