fix(engine): handle matches against any struct

[katafrakt]

Using an "any struct match" (I don't know the proper term, sorry) causes errors being logged during indexing:

14:58:09.984 [debug] Node port message: 
14:58:09.984 [error] Could not expand alias: {:_, [line: 1590, column: 35], nil} at /path/to/file.ex 1590:34

The code causing it is, for example:

  defp normalize_suggestion_data(%_{} = struct) do
    Map.from_struct(struct)
  end

This change adds proper handling to this kind of matches (ignoring them, as they are not useful, but without emitting an error).

[doorgan]

Thanks! It works
Let's just assert rather than crashing the test in the ones I commented and it's good to merge