* Fix typo: invariances ➜ invariants

* Fix comment

* Reduce code duplication in HashMap tests

* Add test api getters for used storage

* Add regression tests for complete storage clearance of nested Lazy's

* Always clear inner cell

* Bring costs of bug fix down

* Apply suggestions from code review

Co-authored-by: Hero Bird <robin.freyler@gmail.com>

* Rename function

* Throw out convenience method, clarify variable names

* Clarify comment

Co-authored-by: Hero Bird <robin.freyler@gmail.com>