authprovider: Fix error return from Credentials when logger is nil

This would segfault if SetLogger had not been called, because
progresswriter.Wrap returns nil when its logger arg is nil, causing
Credentials to return nil, nil.

Signed-off-by: Aaron Lehmann <[email protected]>

Author: aaronlehmann

session/auth/authprovider/authprovider.go

@@ -152,7 +152,7 @@ func (ap *authProvider) Credentials(ctx context.Context, req *auth.CredentialsRe
 		defer ap.mu.Unlock()
 		_, ok := ap.loggerCache[req.Host]
 		ap.loggerCache[req.Host] = struct{}{}
-		if !ok {
+		if !ok && ap.logger != nil {
 			return resp, progresswriter.Wrap(fmt.Sprintf("[auth] sharing credentials for %s", req.Host), ap.logger, func(progresswriter.SubLogger) error {
 				return err
 			})