When adding a condition to an arrow, then unlinking it, it still leaves some leftovers so that the condition is "still there". This may lead to confusion, because the arrow looks like it's not having a condition assigned, but it still does.
Currently, to get a "real" empty condition, one needs to completely remove the error first by clicking on the trash symbol or the "Remove" button, then adding a new one without any condition assigned.
Maybe it's possible to automatically remove the whole contents of the arrow, so that it's a "real" empty condition when unlinked?
Postponed: needs info
1.1
Upstream
This is not a bug in this module, it is something that needs to be reported upstream as that functionality comes form the bpmn.io project.