finalizing logging and multierror

logging/errs.go

@@ -0,0 +1,17 @@
+package logging
+
+import (
+	`errors`
+)
+
+var (
+	// ErrExistingLogger indicates that the user attempted to add a Logger to a MultiLogger using an already-existing identifier.
+	ErrExistingLogger error = errors.New("a Logger with that identifier already exists; please remove it first")
+	/*
+		ErrInvalidFile indicates that the user attempted to add a FileLogger to a MultiLogger but the file doesn't exist,
+		exists with too restrictive perms to write/append to, and/or could not be created.
+	*/
+	ErrInvalidFile error = errors.New("a FileLogger was requested but the file does not exist and cannot be created")
+	// ErrNoEntry indicates that the user attempted to MultiLogger.RemoveLogger a Logger but one by that identifier does not exist.
+	ErrNoEntry error = errors.New("the Logger specified to be removed does not exist")
+)