Any lawful building, structure or use of premises existing at the time of enactment of this chapter, or any subsequent amendment thereof applying to such building, structure or use of premises, may be continued, although such building, structure or use of premises does not conform to the provisions thereof, except as follows:
A. Any undeveloped lot in a subdivision which was not properly approved by the Planning Board and/or not filed in the office of the County Clerk and whose area and/or width and/or depth are less than the specified minimum lot requirements of this chapter shall be considered a violation of this chapter.