Underlying ResourceContainer does not subscribe to ResourceOrigin change monitoring and => is rather vulnerable in the cases when it tries to operate the deleted resources, e.g. expand/collapse a deleted folder:

• Origin throws a resource not found exception, e.g.

  Caused by: info.magnolia.resourceloader.ResourceOrigin$ResourceNotFoundException: No resource found for path /test-module in origin layered
  	at info.magnolia.resourceloader.layered.LayeredResourceOrigin.getByPath(LayeredResourceOrigin.java:105)
  	at info.magnolia.resourceloader.layered.LayeredResourceOrigin.getByPath(LayeredResourceOrigin.java:74)
  	at info.magnolia.resources.app.workbench.ResourcesContainer.getParent(ResourcesContainer.java:297)
  	... 92 more
  

• Container finds nothing better to do than to throw a RuntimeException.
• Since it happens (may happen) during Vaadin rendering phase - it might cause serious consequences for whole Vaadin app (Internal Error, Vaadin Session borked etc)
  See

Ways out:

• either make sure ResourcesContainer somehow synchronises w/ the state of ResourceOrigin
• handle missing resources without runtime exceptions (replace with stubs or smth)