Failing to read config files or hints should cause the verifier to exit early

[danmatichuk]

Currently there are some semi-silent warnings emitted when one of the provided configuration or hint files provided cannot be parsed or has invalid data. This can result in unexpected behavior, since the meaning of the verification result can change drastically depending on the provided information.

The default behavior should be to instead exit with an error if any of the provided files can't be fully interpreted, and add an optional flag to relax this behavior to a warning if the user explicitly requests it.