Revamp logger warning / error behavior

[henvic]

1. An error is not always fatal. Fatal error are better handled by an exception mechanism.
2. Errors and warnings must be sent to stderr instead of stdout. Easily done using console.warn and console.error instead of always relying on console.log.

[protoEvangelion]

We should revisit how we are handling errors across the app.

[protoEvangelion]

Make sure to throw clear error for this: #435