The chapter starts "in medias res" with a description: it recalls the beginning of the book. There is no relationship between the end of chapter three and the situation introduced by the narrative voice in the fourth chapter.
Moreover the reader can't recognize the narrative voice: Susan Barton isn't the one who tells the story here.
The device of telling is mainly used in the chapter, in order to provide to the reader the position of the novelist: he isn't able to conclude the story with a definite true end.
The same description is made twice in the chapter, with a different rendering and thus a different meaning.
The first part has got a lot of details that suggest references to The  Gothic novel: the choice has probably the function of catching the reader's attention.
The adjective faint is used four times in the space of two pages, probably to underline the deadly atmosphere that surrounds the room.
You can surely find a relationship between Eros and Thanatos in the chapter: the absence of light makes the description appeal to touch, and all this recalls body language and sex, moreover there is a direct reference to an "alcove".
The chapter is made up using a lot of poetical devices, for example alliterations and references, especially it recalls the tone and atmosphere of a Eliot's "The Wasteland".
On the contrary the second part of the chapter seems to recreate a senase of truth because it is set at the level of the author (The house of Daniel Defoe).

Moreover it makes the reader reflect on what has already been written about the story, not giving a precise point of reference to the story. It seems meaningless, as Friday has been all along the storyline.

Neither Friday nor Mister Foe were able to provide a definite meaning to other people's vicissitudes: such a close of the novel would probably underline the great difficulty for people to organize their experiences in order to give a sense to their lives. This is a typical example of post-modernist attitude towards  life. Therefore Friday becomes the main character, if you consider the level of the narrator, because his mouth produced a stream of useless words that reflects the condition of post-modern man.