Move to error interception rather than length checking

[bnb]

From https://github.com/cutenode/good-first-issue/pull/80#discussion_r239506631:

If at this point we were to intercept an empty string literal from the response header rather than the results of a list, and this string literal was to be an error response in a short-circuit and no error was able to be parsed, edge of timeouts, parsing errors etc. This would still return as true, hence returning an empty string exposed. It would be suitable at some point here validate the actual type integrity of the expected data formats being used, as side effects of this may lead to false positives.

Referring to bin/good-first-issue#32.