Improve exception handling

[buddhikac96]

Currently, most exceptions are just caught, logged, and rethrown. This is not a good practice. This will cause JVM to write multiple error messages for the same exception. (Eg: YamlUtil.java)

Suggestions

1. Create an own exception library for the Loki and wrap those rethrown exceptions with that.
2. Don't catch and let the caller handle (Recommended)

The first way is not recommended because it is too much for Loki. Just keep KISS.