When a project is deleted from the UI, the plugin tries to remove the view tag twice. The first succeeds, but the second one fails dumping a stack trace in the log. That error message (and the stack trace) is confusing and put me on a ghost hunt trying to understand what went wrong. But nothing was really wrong wrt ClearCase.

First, the plugin removes the view tag in AbstractClearCaseScm.processWorkspaceBeforeDeletion() and then tries to remove it once again in ItemListenerImpl.onDeleted().