NetworkManager gives error on serializing empty NetworkPrefabs array #1843

Steps to produce:

1. Create an empty GameObject and add NetworkManager component to it.
2. You will see the error popping up on the console immediately

Expected behaviour: No errors to be given because an array is empty
Current behaviour: Gives about 9 errors, "Retrieving array element that was out of bounds"

The issue only occurs when NetworkPrefabs array is empty.