It is possible to save Viewport configuration without any content type selected

Steps to reproduce:

1. in a space go to Space Tools → Apps → Viewport,

2. activate a viewport with the default theme → uncheck all options for content type,

3. save the configuration → access the viewport URL for this space.

Expected result:

• the error from the preview is shown, or better

• it is not possible to save a viewport configuration unless at least one content type is selected.

Actual result:
stacktrace appears when trying to access Viewport URL

Workaround:
go to Space Tools → Apps → Viewport → enable at least one of the content types (pages, blogs)