'overlap = portho' causes error on to many clusters

[Dirk]

Hallo,

I'm trying to compile a graph using the attribute overlap = 9:portho. This causes the following error:

abort("Assertion failed: !TREE_EDGE(e), at: ns.c,463,merge_trees"). Build with -s ASSERTIONS=1 for more info.

It occurs on too many subgraph clusters.
The code is no problem on overlap = 9:ortho or overlap = false.

Is there a limit?

All the best
Dirk