Maintenance: improve error wrapping

internal/openvpn/state.go

@@ -1,6 +1,7 @@
 package openvpn
 
 import (
+	"errors"
 	"fmt"
 	"reflect"
 	"sync"
@@ -43,6 +44,8 @@ func (l *looper) GetStatus() (status models.LoopStatus) {
 	return l.state.status
 }
 
+var ErrInvalidStatus = errors.New("invalid status")
+
 func (l *looper) SetStatus(status models.LoopStatus) (outcome string, err error) {
 	l.state.statusMu.Lock()
 	defer l.state.statusMu.Unlock()
@@ -78,8 +81,8 @@ func (l *looper) SetStatus(status models.LoopStatus) (outcome string, err error)
 		l.state.status = constants.Stopped
 		return status.String(), nil
 	default:
-		return "", fmt.Errorf("status %q can only be %q or %q",
-			status, constants.Running, constants.Stopped)
+		return "", fmt.Errorf("%w: %s: it can only be one of: %s, %s",
+			ErrInvalidStatus, status, constants.Running, constants.Stopped)
 	}
 }