chore(updater): shared not enough servers error

internal/provider/mullvad/updater/servers.go

@@ -4,14 +4,12 @@ package mullvad
 
 import (
 	"context"
-	"errors"
 	"fmt"
 
 	"github.com/qdm12/gluetun/internal/models"
+	"github.com/qdm12/gluetun/internal/provider/common"
 )
 
-var ErrNotEnoughServers = errors.New("not enough servers found")
-
 func (u *Updater) GetServers(ctx context.Context, minServers int) (
 	servers []models.Server, err error) {
 	data, err := fetchAPI(ctx, u.client)
@@ -28,7 +26,7 @@ func (u *Updater) GetServers(ctx context.Context, minServers int) (
 
 	if len(hts) < minServers {
 		return nil, fmt.Errorf("%w: %d and expected at least %d",
-			ErrNotEnoughServers, len(hts), minServers)
+			common.ErrNotEnoughServers, len(hts), minServers)
 	}
 
 	servers = hts.toServersSlice()