Index was outside the bounds of the array

Hi there, using the waves.cs file, whenever i increase the dimension while the game is running i get an error:

IndexOutOfRangeException: Index was outside the bounds of the array.
Waves.Update () (at Assets/Scripts/Waves.cs:156)

In addition, whenever i decrease the dimension variable,  the mesh bugs out and only a portion of it is manipulated by the waves.

any help?

thanks