What would the night sky look like if Earth orbited an intergalactic star? If the Earth and its host star were located exactly in-between the Milky Way and Andromeda would the night sky be completely void of light? 

Would stars be visible to the unaided eye?

So there could be a civilization that exists in which the night is completely void of light? …that would suck
Since Andromeda is already visible to the naked eye, to a civilization located at half the distance from the Milky Way, Andromeda would be still be visible. Its total brightness would be four times higher, but since its area would grow by the same factor, its surface brightness would stay constant. The Milky is less bright by a factor of ~2.5, but also smaller, so the surface brightness and hence visibility would be similar.

Individual stars would not be visible except if 1) one exploded as a supernova or 2) the civilization has evolved into beings with extremely large pupils, so that more light is being recorded by their retinas. In fact, we can calculate how large:

According to this list, the brightest star known in the Milky Way is called WR 25, and has an absolute magnitude of $M = -12.25$. Half of the distance from the MW to Andromeda is $d \sim 390,000$ pc, so the distance modulus is
$$\mu = 5\log d - 5 = 22.95,$$
and the apparent magnitude of WR 25 would be
$$m = M + \mu = 10.7.$$

Under the darkest conditions, humans are able to see objects down to an apparent magnitude of ~6, i.e. a factor of
$$f = 2.5^{10.7 - 6} = 75$$
smaller. Thus, to be able to see WR 25, the diameter of the aliens' pupils would have to be a factor of $\sqrt{75} \sim 9$ larger. Since human pupils are roughly 6 mm wide, their pupils would be 5 cm wide, and the eyeballs somewhat larger, incidentally roughly the size of a teacup.

Thus, it seems that my compatriot H. C. Andersen predicted the existence of these beings in his fairytale The Tinderbox.