HOW TO SAVE (MARSHAL_DUMP) WITH CLASS PROC?

I'm using a Pathfinding script (A_Star_Pathfinder) that apparently creates a Proc when defining a part of the pathfinding (reach_method or fail_method).

Problem is that when the player tries to save while a path such as that exists, I get this error:

Script 'Window Save' line 375: TypeError occurred.

that line is: Marshal.dump($game_map, file)

no marshal_dump is defined for class Proc

Any idea how to work around this? Create a rescue function that stops the game from saving if it runs into a problem? Get the "Proc" to save? I don't know what a Proc is or how it works so I'm really lost here.