Fix multierror handling

cmds/portmaster-start/recover_linux.go

@@ -48,7 +48,7 @@ var recoverIPTablesCmd = &cobra.Command{
 
 		if filteredErrors != nil {
 			filteredErrors.ErrorFormat = formatNfqErrors
-			return filteredErrors
+			return filteredErrors.ErrorOrNil()
 		}
 
 		return nil

firewall/interception/nfqueue_linux.go

@@ -153,7 +153,7 @@ func DeactivateNfqueueFirewall() error {
 		result = multierror.Append(result, err)
 	}
 
-	return result
+	return result.ErrorOrNil()
 }
 
 func activateIPTables(protocol iptables.Protocol, rules, once, chains []string) error {
@@ -223,7 +223,7 @@ func deactivateIPTables(protocol iptables.Protocol, rules, chains []string) erro
 		}
 	}
 
-	return multierr
+	return multierr.ErrorOrNil()
 }
 
 // StartNfqueueInterception starts the nfqueue interception.