Crashes application when cached data is available

[withinboredom]

During some resiliency tests to see what happens in various conditions, we noticed a couple of issues:

1. The connection cannot be setup due to missing credentials. This will immediately throw an {{\Exception}} exception, not even trying to load from cache first
2. There is a connection issue, etc (this will only happen if the cache is no longer valid/not used). This will throw Exceptions from a {{Psr18Client}}.

If credentials are missing/invalid but there is a valid cache, it should use the cache (for example, rolling credentials).

If connection issues and an expired cache exist, the cache should still be used until a connection can be re-established, perhaps only logging the issue. If there isn't a cache, it should only throw when trying to use a gated feature (and leave catching an exception to the developer). At least, this is what I would expect.