private void EnsureElementExists(Coordinate a_coordinate)
{
if (a_coordinate.Length != m_dimensions)
{
throw new ArgumentOutOfRangeException();
}
if (m_elements.TryGetValue(a_coordinate, out _))
{
return;
}
var newElement = new GridElement(a_coordinate, this)
{
IsActive = false
};
m_elements.Add(a_coordinate, newElement);
}