Ok, here's a new-and-improved test version (7.0.1770.5) which implements the test (for an attempt to delete a collection element while iterating the collection) at a lower level, where it won't be fooled by code like the example above. But note that it also won't be fooled by my suggested workaround of using another variable in place of the .key($$i) or .NULL references.
It still issues that same error 67 (?Invalid collection operation or reference), which perhaps isn't as clear and precise as it could be (as opposed to, say, "?Illegal attempt to delete an element of collection during iteration"), but I wasn't sure it was worth christening a new error code. For now, let me just repeat that this is a limitation of the underlying Standard Template Library implementation of collections, not an ASB issue per se.
