When logging from a child process, the master logger expects the child process to be be in a wrapper containing at the very least an ID property to work properly (used for identifying which child the message came from).
Notably the logger will work with just a raw child process object though, it will lack the identifier.
The child processes are expected to be attached with the attach() method found in the master logger. This will attatch a listener for the 'message' event.
guard: '_logger', // Message guard, e.g this property has to be true in the IPC message for the logger to read it
debug: false, // On the master logger this determines whether the output is written to console (i.e. will always be written to file), on the client this determines whether it is sent to the master at all
customTypes: [], // Log types, defaults are 'error', 'warn', 'info', 'debug', 'status'. Each one of these has an associated shorthand function, the custom ones will receive one too, e.g. adding 'access' to the custom types will add a logger.access() function