Change behavior of Config.Load method to fail if user-specified config file cannot be loaded

[atc0005]

Current behavior:

// Load attempts to first load the user-specified config file, then falls back
// to checking for a config file in the directory alongside the executable,
// then finally a config file from the user's configuration path. An error is
// returned if the configuration file cannot be loaded.

If the user specifies an exact path to a config file, presumably the intent is to override the use of any default locations? If that user-specified file cannot be loaded, shouldn't that be fatal?