Erroneous reference values yield unhelpful error messages

[eliaspaulpeschke]

Hi!

I was trying to validate JSON data against the URI "#/definitions/Patient" of a schema ( this one ) by creating my validator like this:

function(data, schema, cache_env) {
  if (is.null(cache_env)) {
    ref <- get_json_schema_reference(the_var)
    cache_env$json_validator <-
      jsonvalidate::json_schema$new(
        schema = schema,
        engine = ajv,
        strict = TRUE,
        reference = ref
      )
  }
  cache_env$json_validator$validate(
    json = data,
    verbose = TRUE,
    greedy = TRUE
  )

And had my reference set to wrong values. The error I got was:

Error: TypeError: validator is not a function

Because in this line in js/in.js,
ret = ret.addSchema(drop_id(schema), filename).getSchema(reference);
just turns ret to undefined if the reference is wrong. I think it would be very helpful to add some test here or even return an optional type to R for checking.

Also I think it would be helpful to add info about the use of drop_id and that the base of the URI you need to use is the basename of the file to the function reference. For me, that was a little misleading.

Thanks for your work!