Bits of our language have been picked up from almost every people with whom our English forebears came in contact.
Thus, in remote times, when Norse vikings made settlements along the coasts of England, the Norse gala, “to sing,” entered the native speech.
Thus nahtigala, the early name of the bird Nightingale, merely meant “night singer.”
At some time down through the years, as spelling altered, an n was inserted without rhyme or reason.