Check for existence of a debug_blacklist

[eduardocruz]

This is mix between a feature request and a question. I know that we are not supposed to allow debug mode in production, but even if that happens by accident it would be nice to have a default check to make sure that a debug_blacklist exists, which would mean thought about hiding sensitive keys, instead of just leaving the Laravel default as it is.

If someone has an idea of how could I check that, I can add a pull request. Would be better to just try to read the config file? Or generate an exception and try get information (like keys) from the whoops page? Any suggestions are welcome. Or if you think that this doesn't make sense also.