[BUG]: Not handling errors correctly resulting in a NullPointerException

[jan-bar]

The error is shown in the figure below

The problem code is as follows, manifest may be nil when err != ManifestNotFound

vfox/internal/manager.go

Lines 135 to 142 in 65ee668

	manifest, err := m.fetchPluginManifest(m.GetRegistryAddress(name + ".json"))
	if errors.Is(err, ManifestNotFound) {
	return nil, fmt.Errorf("[%s] not found in remote registry, please check the name", pterm.LightRed(name))
	}
	if err = m.Add(manifest.Name, manifest.DownloadUrl, ""); err != nil {
	return nil, err
	}