Handle nil OCI authenticator with malformed registry

Fixes #896

Signed-off-by: Adrien Fillon <adrien.fillon@manomano.com>

controllers/ocirepository_controller.go

@@ -672,7 +672,14 @@ func oidcAuth(ctx context.Context, url, provider string) (authn.Authenticator, e
  opts.GcpAutoLogin = true
  }
 
- return login.NewManager().Login(ctx, u, ref, opts)
+ authenticator, err := login.NewManager().Login(ctx, u, ref, opts)
+ if err != nil {
+ return nil, err
+ } else if authenticator == nil {
+ return nil, fmt.Errorf("could not authenticate to OCI provider %s with URL %s", provider, url)
+ }
+
+ return authenticator, nil
 }
 
 // craneOptions sets the auth headers, timeout and user agent