You're seeing just the macro log_error, go back to CandleClock.ErrorLogger module for more information.
Link to this macro

log_error(error, log_level \\ :error, metadata \\ [])

View Source (macro)

Formats and logs the given error using Exception.format/3 and Logger.error/1.

Depending on from where this macro is called, it will also include the stacktrace that was recorded with the error in the log message.

error can be anything, special formatting will be done for certain Erlang error atoms or tuples, as well as Elixir exceptions.

log_level (default :error) can be overwritten to log in a different level

metadata optional metadata passed into the Logger