allow providing custom goal?

Let's suppose the we want pathfinder to find "water" from sourceNode ?
How about adding customGoal in the options argument similarly to the heuristic / distance options?

Start by locating the pathfinder entry point and the options handling for heuristic and distance. Trace how a target node is selected, then define completion as accepting a customGoal option that lets the search stop when it reaches the requested goal; check existing tests for pathfinding options and add coverage there.

Written by the indexing model from the issue text.