need some general *nix errs too

logging/errs_nix.go

@@ -0,0 +1,19 @@
+//go:build !(windows || plan9 || wasip1 || js || ios)
+// +build !windows,!plan9,!wasip1,!js,!ios
+
+package logging
+
+import (
+	"errors"
+	"fmt"
+)
+
+var (
+	// ErrNoSyslog indicates that the user attempted to add a SyslogLogger to a MultiLogger but syslog's logger device is unavailable.
+	ErrNoSyslog error = errors.New("a Syslog Logger was requested but Syslog is unavailable on this system")
+	/*
+		ErrInvalidDevLog indicates that the user attempted to add a SyslogLogger to a MultiLogger but
+		the Syslog char device file is... not actually a char device file.
+	*/
+	ErrInvalidDevLog error = errors.New(fmt.Sprintf("a Syslog Logger was requested but %v is not a valid logger handle", devlog))
+)