When i put this in backstage-dynamic-plugins-developer-hub all is fine 
plugins:
  - package: '@internal/plugin-scaffolder@0.1.0'
    integrity: sha512-B9Dvr9CFPYF8kNGfjYv+DkGhl5qbmmePfjIaGwPb4SFMob21i+KQLA7XaLtwNg2GSMsnF2
    disabled: false

However when I put the following then RHDH signin page comes blank

 

   - package: '@internal/plugin-scaffolder@0.1.0'

      integrity: sha512-B9Dvr9CFPYF8kNGfjYv+DkGhl5qbmmePfjIaGwPb4SFMob21i+KQLA7XaLtwNg2GSMsnF2I6enfG0vVCiXetfg==

      disabled: false

      pluginConfig:

        dynamicPlugins:

          frontend:

              internal.plugin-scaffolder:

                scaffolderFieldExtensions:

                  - importName: GenerateUid 

1.2

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With custom field extension gives blank screen

Expected it should show login/signin page