I believe that it comes down to a sequence of intervals being unioned using a reduceRight, which is not tail recursive. Changing to reduceLeft seems to fix the problem. Unfortunately, multiple dependencies are involved.

The problem can last be detected in this project at

which leads to the nxmlreader project

https://github.com/lum-ai/nxmlreader/blob/ef7e1440faf5dcae54cc046ba26825b08f1c84e1/src/main/scala/ai/lum/nxmlreader/standoff/Tree.scala#L57

and then to common

https://github.com/lum-ai/common/blob/b7c0b70c460790088d655a98be178cbef9767a24/src/main/scala/ai/lum/common/Interval.scala#L399